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The Science and Practice of

Cheese-Making

A Treatise on the Manufacture of Amer
lean Cheddar Cheese and other varieties

intended as a text-book for the use of dairy teachers and

students in classroom and workroom ; prepared also

as a handbook and work of reference for the

daily use of practical cheese-makers

in cheese-factory operations

Lucius L. Van Slyke, Ph.D.

Chemist of the New York Agricultural
Expeiiment Station

and

Charles A. Publow, A.B., M.D., CM,

Associate Professor of Dairy Industry in the Neiu York State
College of Agriculture at Cornell University

Illustrated

New York

Orange Judd Company

1921

LONDON

KEGAN PAUL, TRENCH, TRUBNER & Co., Ltd.

BROADWAY HOUSE, 68-74 CARTER LANE, E.G.

. V3

""^z .

1909

Orange Judd

Company

New York

^Printed in U. S. A. J

PREFACE

This book has been prepared to supply a need
definitely expressed by dairy teachers, dairy stu-
dents and cheese-makers. To meet the require-
ments of to-day, a book on cheese-making must be
something more than a mere description, in a
recipe-like form, of certain operations to be per-
formed ; it must also make prominent the reasons
for each step in every operation and present as
clearly as possible the facts and principles under-
lying the methods ; in other words, it must present
the science as well as the practice of cheese-making.

Knowledge of cheese-making, as of any art, is
two-sided, practical and scientific. Practical knowl-
edge tells us zt'hat to do; scientific knowledge gives
us the reasons for what is done. Practice consists in
doing things ; science, in knozving things. Knowledge,
to be complete, must be both practical and scientific;
we must know not only zuhat particular things to do
but zvhy we do them. Just in proportion as the prac-
tical and the scientific sides of knowledge advance
together, does the practice become more nearly per-
fect. The more one knows, the more and better can
one do.

The practice of cheese-making embraces a systematic
series of mechanical operations, which have been
gradually developed by experience and observation.
In its widest application, it includes (i) the produc-
tion and care of milk: (2) the conversion of milk
into cheese; and (3) the care of the manufactured
product until it is ready to be used as food.

VI PREFACE

The science of cheese-making embraces a collection
of the underlying facts and principles relating to
the practice, arranged in systematic form so as
to show their relations. For example, it includes,
among other lines: (i) A knowledge of the con-
stituents of milk — what each has to do in the mak-
ing of cheese and how each is related to the yield,
composition and quality of the product; (2) the
changes which each constituent of milk may under-
go and the effect of such changes upon the yield,
composition and quality of cheese; (3) the action of
micro-organisms upon the constituents of milk and
of cheese; (4) the effect of unorganized ferments
upon milk and cheese; (5) the effect of temperature,
humidity and other conditions upon the chemical
changes that take place during the operations of
cheese-ripening.

While cheese has been made for thousands of
years, the growth of accurate, systematic knowledge
regarding its inner details has been extremely slow;
but within the past twenty years there has been an
era of unprecedented activity in the investigation of
the chemical, biological and other problems con-
nected with milk and cheese. As the result of the
application of new knowledge thus gained, the prac-
tice of cheese-making has undergone marked im-
provements. The problems that are peculiar to the
manufacture of American cheddar cheese have been
studied extensively in the United States and Can-
ada, mainly under government direction In some
form, and more especially at agricultural experi-
ment stations. Two institutions have been promi-
nent for the extent and thoroughness of their

PREFACE VU

investigations and for the far-reaching influence of
the results of their work — the agricultural experi-
ment stations of the states of Wisconsin and
of New York (Geneva). The results of these and of
other useful investigations are not now easily avail-
able, being scattered through many reports and
bulletins, most of which can be found only in large
libraries. One of the tasks proposed at the outset
in the preparation of this book was to digest this
large mass of valuable material and present the
results in systematic form, thus making it for the
first time readily available to all dairy students. An
exhaustive, detailed history of these investigations
would compel one to present some results and in-
terpretations which more accurate work has later
shown to be erroneous. Those' for whose use this
book has been prepared are more interested in
knowing what the status of our present knowledge
is than in studying the various details which have
preceded. The chief aim, therefore, has been to
digest and summarize the results of investigation
in such a way as to give what, in the light of our
present knowledge, we may now regard as the
probable facts and their proper interpretation. This
task is a somewhat discouraging one, because new
facts are being rapidly added to our knowledge
and, in consequence, what we may now hold as
true is quite likely to need modification in the near
future.

The main portion of this book is devoted to
cheddar cheese for the obvious reason that this is
the kind most extensively made in America. A
few other kinds of cheese are briefly discussed, so

Viil PREFACE

far as the assigned limits permit. Even in relation
to cheddar cheese, the book is not intended as an
encyclopedia, but an effort has been made to have
it reasonably complete.

The language used by the practical cheese-maker
in describing the operations of cheese-making has
inevitably expressed his theories or explanations
of observed facts. Many expressions have persisted
even after they were known not to be in accordance
with facts. It has seemed highly desirable that
such inaccuracies should be corrected and the lan-
guage made to correspond with our advanced
knowledge. In addition, there have been many in-
accurate and loose expressions in common use
which have come simply from carelessness and lack
of precision. Such expressions have been carefully
revised in the preparation of this book.

A few words in regard to the general plan of the
book will not be out of place here. The subject
matter is divided into five parts. The first part is
devoted mainly to a description of the operations
employed in making American cheddar cheese un-
der normal conditions, including the care of cheese,
factory construction, equipment, etc. This portion,
of the subject is placed first in order in the book,
as a matter of convenience, because it is the por-
tion which will be most commonly referred to in
connection with practical work. In order to avoid
overloading the description of methods of cheese-
making with too many details in the way of ex-
planations, precautions, etc., many of these points
are discussed with fullness in later portions of th'^
book, appropriate references being given in pan

PREFACE iX

first. The second part is devoted to a study of the
various defects that may occur in cheese as the
result of abnormal conditions in the process of
cheese-making. The third part, which comprises
more than one-half of the book, is devoted to the
science of cheese-making. This is the first attempt
to treat the subject in a comprehensive, systematic
manner. It is realized that not all of the chapters
will appeal equally to those who use the book. For
a satisfactory understanding of Chapter XXIV,
some knowledge of chemistry is required. The
fourth part of the book contains a description of
methods of making some other varieties of cheese
than American cheddar. In the fifth and last part
are given a description of the tests used in cheese-
making, an indexed bibliography of the subject, and
other matter of a miscellaneous character.

Each illustration has been carefully selected with
reference to giving supplementary, helpful, and
specific information. The use of illustrations as a
means of padding the book, or as a source of en-
tertainment without reference to the subject-mat-
ter, has been carefully avoided.

In using this book, teachers will adapt it to the
special conditions under which they work or to
the special purpose they have in mind. For ex-
ample, the amount and kind of matter studied will
dififer in the case of short-course and of long-course
students. Material will be found for those most ad-
vanced, as well as for beginners. Good judgment
will need to be exercised in respect to the combi-
nation of the diflferent parts, but assistance in this
respect is given by means of specific references. It

X PREFACE

is not expected that any book, however complete
and clear, will enable one to make cheddar cheese
successfully without the help of a competent
teacher.

It is appreciated that, in the preparation of a
work on new lines, the results are inevitably far
from perfect. Those who have occasion to use this
book will confer a favor if they will be free to call
the attention of the authors to any defects which
they find, whether in the line of omissions, incom-
plete treatment or inaccuracy of statement.

As to the respective shares of the work for which
the authors are severally responsible, Chapters II,
III, IV, V and XXVII represent combined work;
Mr. Van Slyke has written, for the most part,
Chapters I, VI and VIII; Mr. Publow, except for
some minor changes and additions, has written
Chapters VII and IX to XIII inclusive; Mr. Van
Slyke has written Chapters XIV to XXVI inclu-
sive, and also Chapters XXVIII to XXX.

We desire here to express our appreciation of
valuable assistance received in various ways from
the following persons: Mr. G. G. Publow, King-
ston, Ontario, Canada, Chief Dairy Instructor in
cheese-making; Mr. George A. Smith, Geneva,
N. Y., Dairy Expert at the New York Agricultural
Experiment Station; Mr. Alfred W. Bosworth,
Geneva, N. Y., Associate Chemist at the New York
Agricultural Experiment Station; and Dr. Donald
D. Van Slyke, New York City, Assistant Chemist
at the Rockefeller Institute for Medical Research.

September, 1908.

CONTENTS

PART I.

Page

The Manufacture of American Cheddar Cheese.

I.
The Care of Milk for Cheese-Making . , . , 3

II.
Preliminary Steps in Making Cheddar Cheese , » 15

III.

Operations from Cutting Curd to Salting .... 25

IV.
Operations from Salting Curd to Removal from Press . 37

Moisture and Acidity in Curd and Cheese: Conditions,

Effects and Control . 45

VI.

Modifications of Cheddar Process and Miscellaneous

Subjects , 55

VII.
Care, Shipment and Sale of Cheese .... 71

VIII.

Commercial Qualities of Cheddar Cheese and Methods of

Judging ^ . . . 80

IX.
Cheese- Factory Construction ..... o 97

X.
Cheese-Factoiy Equipment ... c - * 106

Xll TABLE OF CONTENTS

_ Page

PART II.

Defects of American Cheddar Cheese: Causes,
Remedies and Means of Prevention.

XI.
Defects in Flavor . . 115

XII
Defects in Body and in Texture . , , , , 121

XIII.
Defects in Color and in Finish ...,,, 129

PART III.

The Science of Cheese-Making: The Chemical, Bio-
logical and Other Relations of Milk and Cheese.

XIV.
The Constituents of Milk 139

XV.

Conditions Affecting Proportions of Constituents in Milk . 155

XVI.
Functions of Milk Constituents in Cheese-Making . . 177

XVII.

Milk Constituents and Yield of Cheese . . . 186

XVIII.
Methods of Calculating Yield of Cheese . . . .211

XIX.

Milk Constituents in Relation to Composition of Cheese . 231

XX.

The Composition of Cheese in Relation to Quality . . 243

XXI.

Methods of Paying for Milk for Cheese- Making . . 253

TABLE OF CONTENTS Xlll

Page
XXII.

The Relations of Micro-Organisms and Enzvms to Cheese-
Making 285

XXIII.
The Ripening of Cheese 313

XXIV.
Chemical Changes in Cheese-Ripening . , . . S?*^

XXV.

Causes of Chemical Changes in Cheese-Ripening , . 354

XXVI.

Commercial Relations of Cheese-Ripening . . . 379

PART IV.

XXVII.
Methods of Making Different Varieties of Cheese . , 397

PART V.

Methods of Testing, Factory Organization
and Literature.

XXVIII.
Methods of Testing Used in Cheese-Making . . . 423

XXIX.

Cheese-Factory Organization and Management . , 447

XXX.
llie Literature of Cheese-Mak'ng . . . • 454

ILLUSTRATIONS

Page

Aiiicrican Cheddar Cheese Frontispiece

M'icroscopic Appearance of Clean Milk 4

Microscopic Appearance of Unclean Milk .... 4

Sicnitary Milking-Pails 10

Aerator and Cooler 11

Dipper for Use in Cheese-Making 20

McPherson Hand-Agitator for Stirring Curd ... 28

Double-Toothed Curd-Rake ,29

Effect of Excessive Moisture in Soaked-Curd Cheese . 58

Abnormal Texture of Soaked-Curd Cheese .... 59

Weighing, Paraffining and Boxing Cheese .... 74

Apparatus for Paraffining Cheese 75

Appearance of Perfect Cheese-Box 1?>

Close-Textured Cheese 84

Loose-Textured Cheese 84

Texture of Sweet -Curd Cheese 84

Texture Caused by Gas 85

Mechanical Holes in Cheese 85

Swiss-Holes 86

Design for Septic Tanks 101

Cold-Air Circulation in Curing-Room ...... 102

Plan Showing Arrangement of Cheese-Factory Equip-
ment 103

Plan for Cheese-Factory 105

Steel Cheese-Vat 107

Barnard's Curd-Cutter 108

Gosselin Curd-Mill 108

Continuous-Pressure Gang-Press 109

Eraser and Wilson Hoops 110

Apparatus for Showing Humifl 11-7 in A:t . . . . '•11

Fish-Eye Texture in Yeasty Cheese 126

Seamy Color and Lack of Pressure 131

Brine-Soluble Protein of Cheese Drawn out in Strings . 148

Diagram Showing Composition of Milk 195

Distribution of Milk-Constituents in Cheese and Whey 196

Yield and Composition of Cheese from Different Milks 206
Yield and Composition of Cheese from Milks of Different

Breeds 208

Xvi ILLUSTRATIONS

Page

Effect of Skimming Milk on Composition and Yield of

Cheese » 235

Ball-Shaped Bacteria . . . 287

Chains of Ball-Shaped Bacteria . . „, . . . . 287

Rod-Shaped Bacteria 288

Bacteria with Swimming Hairs 288

Effect of Temperature on Bacteria 290

Lactic Acid Bacteria 292

Close-Textured Cheese Ripened at Different Tempera-
tures 324

Sweet-Curd Cheese Ripened at Different Temperatures 325
Devices for Keeping Records of Temperature . . 384-385

Appearance of Frozen Cheddar Cheese 390

Edam Press-Mold and Cover 412

Cross-Section of Edam Press-Mold and Cover . . . 413

Edam Salting-Mold in Cross-Section 413

Edam Salting-Mold, Inside and Outside Appearance . 414

Parts of Gouda Mold Shown Separately . . . . 418

Parts of Gouda Mold United .. ^ ..... 418

Part I

The Manufacture of American
Cheddar Cheese

Details of cheese-making operations
from care of milk to sale of cheese.

Commercial qualities and methods
of judging.

Cheese - factory construction and
equipment.

The Science and Practice of
Cheese-Making

CHAPTER I

The Care of Milk for Cheese-Making

One of the fundamental requisites of successful
cheese-making is clean milk. The cheese-making
process begins in reality on the premises of the milk
producer; and, of all the details of the process, the
one that is, and has always been, productive of most
trouble is the improper handling of milk by patrons.
There has usually been complete absence of any ade-
quate method in caring for milk. The occasional
skimming or watering of milk always calls forth the
severest condemnation, and properly ; but actual losses
caused dairymen in this way are insignificant in com-
parison with the losses caused by carelessness and
neglect in properly caring for milk. It is to be hoped
that the time may come when deliberate carelessness
and indifference in the production and care of milk
will be regarded as little short of criminal. The value
of milk in cheese-making depends, in no small degree,
on the care it receives from the time it is drawn from
the udder until it is delivered at the factory. The
quality of milk in respect to its cleanliness determines,
to a great extent, the quality of cheese that can be
made from it.

4 SCIENCE AND PRACTICE OF CHEESE-MAKING

When milk is not properly cared for by patrons, it
may acquire undesirable characteristics, which injure
its usefulness in cheese-making, such, for example, as
high acidity, offensive odors and tastes, formation of
gases, etc.

The causes of these defects will be briefly con-
sidered under four headings: (i) Bacterial infec-
tion, (2) absorption of flavors, (3) food eaten, (4)
physiological or disease processes in cows.

o°» .ops
Oo!

o c

o O I J 0

O o

•<P"' '^•^ o 0^6 O

o O " ^ • o . O o ^ o O

o90

0 ,

o°oo o " O

0^0 o O Q o

°6 °°°

FIG. 1

Appearance of clean milk under
the microscope. Only fat^globules
are seen.

.Oo

9c^ .

O •
o

.0°.

8 o

°° oO o, o 0.9

".•?oO G - ^

t' - o

FIG. 2

Appearance of unclean milk vmder the
microscope. The lisrht, round bodies are
fat-globules; the dark masses are groups
of bacteria and cellular matter.

SOURCES OF BACTERIAL INFECTION

Milk, when drawn with careful precautions from
the udder of a cow, contains comparatively few
bacteria; but milk obtained and handled under ordi-
nary conditions is found to contain large numbers,
often several hundred thousand, in one cubic centi-
meter (somewhat less than one-quarter of an ordinary
teaspoonful). The more dirt there is in milk, the

CARE OF MILK FOR CHEESE-MAKING 5

more bacteria there will be. Bacteria and dirt always
go together in dairy matters. The relations of bac-
teria to milk are considered in greater detail in
Chapter XXII, p. 285.

The most common sources of bacterial infection are
the following: (i) Unclean or unhealthy condition
of cows; (2) unclean condition of stables or places of
milking; (3) unclean condition of persons milking
cows; (4) unclean condition of utensils used; (5)
keeping milk in unclean surroundings, and especially
at temperatures above 60° F. after milking.

Unclean condition of cows. — The hair on cows
favors the accumulation of dirt and dust. The con-
dition is worse in proportion as cows are not regu-
larly and thoroughly cleaned. Dust particles and
hairs, laden with bacteria, are in position to drop into
the milk-pail. While the hairs and coarse chunks of
dirt may be removed from milk by straining, the
bacteria are, in large part, washed off into the milk
and cannot be removed by any ordinary process of
straining.

Unclean condition of stable. — A dirty condition
of the floors, walls and ceilings of a stable tends to
contaminate milk. Any condition in the stable that
affords a supply of floating dust at the time of milking
furnishes additional bacteria for milk

Unclean condition of milker. — The hands and
clothing of a milker may easily be loaded with bacteria
and thus become a source of infection. Particularly JK y/
objectionable is the filthy practice of moistening the /^

hands with milk when milking. ^^. ^-y^y

Unclean utensils, especially the milk-pails, strain- ^
ers and milk-cans. The cracks and joints of all

6 SCIENCE AND PRACTICE OF CHEESE-MAKING

utensils made of tin, unless great care in cleaning is
used, contain dirt that holds large numbers of bacteria.
Rust and imperfect soldering of joints furnish places
for dirt to get out of easy reach. Without prompt
^r .^^.w^nd extreme care, strainers easily become filthy and
i^sv'/^/^are then simply breeding places for bacteria. When
,^^c^^ milk cans are used for carrying back whey to the farm
from the cheese-factory, the cans often are not cleaned
promptly, and, when finally attended to, are not treated
with proper thoroughness. Through the medium of
a dirty whey-vat, filth, as well as disease, germs
may be distributed throughout the whole neighbor-
hood. Even epidemics of typhoid fever have been
traced to this source of infection; certain diseases
have been similarly distributed among farm ani-
mals, as, for example, tuberculosis in calves and
hogs.

Unclean surroundings after milking. — Milk, even
when drawn under the cleanest possible conditions,
very easily becomes contaminated by being kept, even
for a short time, in any place that is not clean.

Keeping milk cool. — At temperatures above 60°
F., milk more rapidly undergoes fermentation changes
than at lower temperatures (p. 290).

ABSORPTION OF FLAVORS

Milk, particularly when warm, possesses remarkable
ability to absorb and retain odors present in the sur-
rounding air. The most common sources of such
odors are the manure in unclean stables and any
strong-smelling food present in the stable during milk-
ing-time. Among the most common conditions under

CARE OF MILK FOR CHEESE-MAKING 7

which undesirable flavors are absorbed are the keep-
ing of milk in or near cellars, silos, stables, pig-pens, or
any place where strong-smelling substances of any
kind are present.

FLAVORS FROM FOOD EATEN

Certain foods that have strong taste and odor Im-
part to milk their characteristic flavors wlien eaten
within a few hours before milking. Most common
among these are onions, garlic, ra^e^ turnips, leeks^
cabbages, ragweed and decayed ensilage^ Experi-
ments have shown that with most of these the effects
are largely, if not entirely, avoided when milk is not
drawn for 8 to 12 hours after such food is eaten,
provided an abnormal amount has not been taken.
Similar results, but in milder form, may come from
the feeding of excessive quantities of such materials
as swill, brewers' grains and distillery slops. It is
a safe rule, in the case of milk to be used for cheese,
not to use at all such foods as are in danger of taint-
ing milk, such as turnips, cabbages, rape, etc., and to
keep cows where they cannot get at anything that
may endanger the quality of the milk for cheese-
making. Some green fodders, like second-growth
clover, rye, etc., have been found to produce gassy
and tainted milk and cheese. Such a condition is
more likely due to bacteria on these foods than to
any peculiar property in the foods themselves.

There is one marked point of difference between
bad flavors of bacterial origin and those coming from
absorbed flavors and strong-smelling food. The
latter manifest their presence in the milk clearly

8 SCIENCE AND PRACTICE OF CHEESE-MAKING

when the milk is dehvered at the factory and may
be largely removed by proper aeration and care
in the cheese-making operations ; but those of
bacterial origin do not usually reveal their presence
until the cheese-making process is well along, or not
even until the cheese has been made and acquired
some age.

PHYSIOLOGICAL OR DISEASE PROCESSES

IN COWS

It is well known that if a cow is abnormally
heated or excited just before milking, tainted milk
and cheese may result. Such a condition may be
brought about by dogging cows or any form of
ill treatment. Many diseases directly affect cow's
milk and render it unfit for use in making cheese.

HOW TO OBTAIN CLEAN MILK

We have seen that the one chief source of bacteria
is dirt. Hence, the one thing needful to prevent
bacteria getting into milk is extreme cleanliness at
every point of contact with the milk. The following
suggestions are given to indicate what is meant by
cleanliness in connection with milking and caring for
milk.

Cows should be clean and healthy. — Too much
pains cannot be taken to keep cows clean. In ad-
dition to regular currying and brushing all over, the
udder and adjacent portions of the body should be
carefully brushed before milking and also wiped with
a damp, clean cloth. The udder should also be wiped

CARE OF MILK FOR CHEESE-MAKING 9

after milking. The best way to clean the parts is by ^^^.^^-o-^^
using warm water and a cloth. The cleaning is made ...-vcr«

easier by clipping the hair close to the abdomen, udder
and flanks. Dry-brushing of the udder before milking
should not be practiced, as it makes conditions worse
by stirring up dust which settles into the milk-pail.

The stable. — Every condition about the stable
should be regulated with reference to absence of dirt,
an abundant supply of pure air, and a direct exposure
to sunlight. The floors should be tight and of a ma-
terial not readily absorbing liquids. An abundance of i^^^-ty^^-
clean bedding should be used, and the manure should
be removed more frequently than once a day, and, in
any case, not immediately before milking. The walls
and ceiling should be swept often enough to prevent
the accumulation of dust, but never just before milk-
ing-time. Once a year, at least, it is wise to clean y^^/^^ .
the entire stable with extreme care and then go over y^^^^^^
the whole with a generous coat of whitewash. At
such a time the stable should be thoroughly disin-
fected if there has been any contagious disease in
the stable. The surroundings outside of the stable
should be kept in a clean condition, so as not to in-
terfere with the supply of pure air. Where water
pressure can be had, as in case of a windmill, storage
tank, etc.^ hose should be used in cleaning.

Milking. — The milker should wash his hands care-
fully before milking and have them perfectly dry while y.^^^ ^,
milking. It is also desirable to have a special coat or ^^ ^,crz<^
jacket for milking, made of some material that will
not catch or hold dust easily. Only small-top milking- .^.g^^^^^U^
pails should be used. (Fig. 3.) z,^^^ -^^r:?!^^^'^*^

10 SCIENCE AND PRACTICE OF CHEESE-MAKING

Cleaning dairy utensils. — All utensils that come
in contact with the milk, such as milk-pails, milk-cans,
aerators, etc., should be made of metal, preferably of
pressed tin, with smooth, well-flushed joints and per-
fect seams. They should be kept entirely free from
rust. Such vessels should never bse allowed to dry
when dirty, as dried particles of milk are particularly
difficult to remove. In cleaning dairy utensils, rinse
them first, with cold or lukewarm water; and then
scrub with a brush, using water containing some good
washing-powder that will remove grease. Then scald

FIG. 3 — DIFFERENT STYLES OF SANITARY MILKING-PAILS

with boiling water and complete the cleansing, if pos-
sible, by exposing to a jet of live steam for three to
five minutes. Never dry with a cloth, but, when
practicable, expose the utensils finally to direct sun-
light for a few hours. Dust and flies should be pre-
vented from entering the cans after washing.
Strainers should be washed immediately after
using, cleaning first in tepid water, following with
hot water and soap or washing-powder and^ finally
with hot water and then with steaming or boiling.

Treatment of milk after milking.— As soon as
each cow is milked, the milk should be removed from

CARE OF MILK FOR CHEESE-MAKING

the stable to some room free from all odors and
with cleanly surroundings. The milk should be at
once strained through a brass-wire strainer, having
not less than fifty meshes to the inch, and also
through three or four thicknesses of cheese-cloth. Still

FIG. 4

A quick way of cooling milk. The milk In a thin
feyer runs over a surface made cold by running Ice-
water. The same water can be used repeatedly by
\dding Ice each time. This method should be used
only when the surrounding air Is pure.

FIG. 5

The milk contained in
these long "shot-gun" palls
or cans, placed in ice-water
Is stirred occasionally to
Insure even cooling.

more effective results in straining can be secured by
the use of absorbent cotton, though its expense may
make its use impracticable under ordinary conditions.
After straining, cool at once to 60^ F,, or better to
50° F., by ice or cold water. (Figs. 4 and 5.)

^^ -^^^ /".

tf-^^

^f^^/^-i^f^f"^!^^-

'..^^

12 SCIENCE AND PRACTICE OF CHEESE-MAKING

Under usual conditions, it is best to cool the milk
^v^^j^ with as little exposure to air as possible and then cover
it when milking is completed. '

Aeration, if needed (p. 120), should be carefully per-
formed as follows for the best results : ( i ) Aeration
should take place only in a pure atmosphere. (2) Aera-
tion should be performed at body temperature and
therefore is best done immediately after milking. (3)
Aeration should precede cooling and not be simultan-
eous with it. (4) Aeration should be carried out over
the most extensive surface possible and as slowly as
possible. Under ordinary farm conditions aeration is
better not attempted.

Feeding-time. — Foods having marked odors should
be fed only after milking and then at once, and none
should be left in the stable. Drv fodders, which
furnish dust, should likewise be fed after milking.

Diseased milk. — The milk of diseased animals

f should not be used nor that of animals fresh in milk
before the ninth milking. Colostrum milk (p. 158)
should never be used for cheese-making. The presence
of such milk seriously affects the operations of cheese-
making in the following manner : Soon after cutting,
the curd becomes softer and will not firm sufficiently
to make good cheese.

Contagious diseases. — No person suffering from,
or recovering from, a contagious disease, nor any per-
son that has anything to do in caring for such a
person, should be allowed to have any contact with
the dairy.

JUDGING MILK FOR CHEESE-MAKING

The only solution of the problem of obtaining clean
milk for cheese-making lies in the education of the

CAkE OF MILK FOR CHEESE-MAKING I3

milk producer. It is necessary to do more than dis-
tribute printed instructions. Personal inspection of
individual farm premises is also necessary. But it is
essential, in addition to these methods of education,
to g-ive some additional specific inducement which will
impress each patron as nothing else will and lead him
to recognize not only the general importance of pro-
ducing clean milk, but the application to him person-
ally. The most effective means of making a deep
impression is to give each one an opportunity to see
how far his milk departs from the recognized standard
of milk that is clean enough for making good cheese.
These results can be realized by the introduction of a
system of judging milk; and if the results of each
judging can be made to affect the dividends, the pa-
tron soon realizes how near or how far from the
proper standard his milk is.

The following method is suggested as an effective
one in judging cheese-factory milk: Examine the
milk for (i) acidity, (p. 426); (2) dirt in suspen-
sion, (p. 434) ; (3) micro-organisms by the fermen-
tation test, (p. 434) ; and (4) flavor. Use the fol-
lowing scale of points for scoring milk:

When perfect

Acidity 15

(Acidity not over 0.18 per cent.)

Dirt IS

(No dirt in suspension.)

Fermentation test 45

(No signs of abnormal ferments.)
Flavor 25

(Entire freedom from abnormal odor and taste.)

In each milk, the score is diminished in the case of
each quality if the milk shows any imperfections. This
system will be found effective in application, If the

14 SCIENCE AND PRACTICE OF CHEESE-MAKING

judging is done carefully and the results made known
to the patrons. If patrons can be persuaded to apply
the results of such judging to the distribution of divi-
dends, the work would be more effective, of course.
For example, a patron's dividend could be marked
down one cent per lOO pounds of milk for each ten
points his milk scored below lOO on the above system.
Of course, this method does not apply to cases in
which the milk is obviously bad when brought to the
factory. The only remedy in such cases is to refuse
the milk altogether.

This is a matter which should be discussed at the
annual meeting of patrons, in case of co-operative
factories, when some definite policy should be adopted
and intelligently enforced. For a more complete treat-
ment of the subject of judging and scoring milk, see
Modern Methods of Testing Milk and Milk Products,
pp. 182-192 (published by the Orange Judd Co.).

CHAPTER II

Preliminary Steps in Making
Cheddar Cheese

In entering upon the detailed study of the methods
of cheese-making, we shall present the subject in ac-
cordance with the following outline of the different
steps in the various operations that are performed:

(1) System of keeping records of the operations of

cheese-making.

(2
(3
(4
(5

(10

(11
(12

First care of milk at the factory.

Ripening the milk.

Adding color.

Coagulating the milk by rennet.

Cutting the curd.

Heatmg the curd.

Removing the whey from the curd.

Cheddaring the curd.

Millmg the curd.

Salting and pressing curd and dressing cheese.

Care, shipment and sale ot cheese.

In describing the details of the methods of making
American cheddar cheese, we shall limit our treatment
largely to normal conditions, reserving for separate
treatment abnormal conditions (p. 115). An
effort is made not to overload the description with
unnecessary details. The explanation of many de-
tails is given in other chapters, to which reference
will be made as needed, instead of incorporating
them with the description of the cheese-making
operations,

l6 SCIENCE AND PRACTICE OF CHEESE-MAKING

SYSTEM OF KEEPING RECORD OF THE
OPERATIONS OF CHEESE-MAKING

Few manufacturing processes require more careful
and more skilled mechanical manipulation than does
cheese-making; none demands more responsibility and
intelligence. A successful cheese-maker must be quick
to think and to act; he must know the details of
his process and the principles underlying these de-
tails, and be able to apply his knowledge in con-
trolling variations caused by climatic, biological and
chemical conditions. In beginning his daily work,
a maker should have clearly in mind the ideal
he wishes to realize in the finished cheese, and
should conduct his work with this end in view. It is
absolutely essential to the highest success to keep daily
records of the details of the work for constant refer-
ence. Below, we give a detailed blank form, and
advise all cheese-makers and students of cheese-
making to make constant and faithful use of it in
their daily work:

1. Vat used (number of vat).

2. Condition of milk (flavor, temperature, acidity).

3. Amount of milk in vat pounds.

4. Fat in milk per cent. Casein in milk per cent.

5. Ripeness of milk by —

1. Acidity-test per cent of acidity.

2. Marschall rennet-test spaces.

3. Monrad rennet- test seconds.

6. Kind of starter used Acidity per cent.

7. Amount of starter used pounds.

8. Time when starter was added a. m. p. m.

9. Amount of color added.

10. Kind of color used.

11. Temperature of milk when rennet was added degrees F=

12. Ripeness of milk when rennet was added —

1. By rennet-test seconds or spaces

2. By acidity-test per cent.

13. Time when rennet was added a. m. p. m.

14. Amount of rennet (or pepsin) used ounces or grams.

15. Amount of rennet (or pepsin) used per 1,000 pounds of

milk ounces or grams.

16. Time when curd was cut a. m. p. m,

17. Time in coagulating minutes.

FIRST STEPS IN CHEESE-MAKING XJ

18. Condition of curd when cut (hard, soft, etc.).

19. Time when heating began , ,a. m. p.m.

20. Acidity-test of whey when heating began , per cent.

21. Temperature to which milk was heated after cutting, etc degrees F.

22. Time at which temperature was reached a. m. p. m.

23. Test when whey was removed —

1. By hot-iron test ' inches.

2. By acidity-test per cent.

24. Time at which whey was removed a. m. p. m.

25. Time from cutting curd to removal of whey hours minutes

26. Amount of fat in whey per cent.

27. Condition of curd (sweet, tainted, solid, gassy, floating, etc.).

28. Time when curd was milled a. m. p. m.

29. Length of string on hot iron when curd was milled inches.

30. Acidity-test of whey-drippings when curd was milled per cent.

31. Time when curd was salted . a. m p. m.

32. Acidity-test of whey running from curd just before salting per cent.

33. Amount of salt used for 1,000 pounds of milk pounds.

34. Kind of salt used.

35. Time when curd was put in press a. m. p. m.

36. Temperature of curd when put in press degrees F.

37. Condition of curd when put in press.

38. Kind of cheese made.

39. Number of cheeses made.

40. Time when cheese was dressed a. m. p.m.

41. Time when cheese was pressed a. m. p. m.

42. Time when cheese was taken from press a. m. p. m.

43. Weight of green cheese pounds.

44. Average amount of milk per pound of cheese pounds.

45. Amount of cheese from 100 pounds of milk pounds.

46. Amount of cheese made for 1 pound of milk-fat pounds.

47. Weather conditions (temperature, humidity etc.).

48. Amount of cheese from 100 pounds of milk calculated by

formula 6 (p. 225).

Special remarks. — (Include here any deviations from the usual modes
of procedure not included in the foregoing list.)

FIRST CARE OF MILK AT THE FACTORY

Each can of milk, on arriving at the factory, should
be carefully examined for acidity, cleanliness and ab-
normal flavors (p. 426). If any is sour or of bad
flavor it should not be accepted. When any patron's
milk is suspected, from the results of these tests, of
containing ferments that work harm in cheese-making,
the milk should be subjected to the fermentation test
(p. 434). At any time when abnormal fermentations
make trouble, each patron's milk should be thus
treated until the source of trouble is located. For a
quick test for acidity, see p. 428. When weighed, the

l8 SCIENCE AND PRACTICE OF CHEESE-MAKING

milk should be strained through two layers of clean
cheese-cloth to remove all insoluble dirt (p. 434).
While the milk is accumulating in the vat, it should
be stirred frequently up to the time of coagulating
with rennet in order to keep the cream from separ-
ating. When the vat is full enough, the amount of
milk present is figured, and the acidity of the milk
is determined or a rennet-test made.

RIPENING MILK

This consists in the formation of a certain amount
of lactic acid (p. 292). Its object is to control more
completely the various operations of cheese-making;
this is accomplished especially (i) by the repression
of abnormal ferments; (2) by assistance in shrinking
curd, expelling whey, and maturing the curd in body
and texture. Lactic acid may be formed by allowing
milk to stand a while at a temperature of about 86° F.
When lactic acid bacteria are not present In abundance
or are kept back in growth by injurious organisms, it
is necessary to use a starter or culture.

Preparation of starter. — A starter is a material
(usually milk), containing large numbers of lactic
acid organisms, which is added to milk or cream
for the purpose of causing lactic fermentation. Start-
ers are of two kinds: (i) Natural and (2) com-
mercial. ( I ) Natural starters. — A natural starter
may be prepared as follows : Milk of the best possible
character, taken under precautions necessary to insure
cleanliness, is heated to 90° F. for one hour, aerated in
a pure atmosphere, and immediately cooled to 65° F.
In 24 hours the milk should be sufficiently sour to be
ready for use. Some of this starter may be used in

FIRST STEPS IJ^ CHEESE-MAKING I9

preparing a starter for the following day, putting a
little into some skim-milk that has been heated to i8o°
F. for 30 minutes, cooled to 70° F., and then allowed
to stand 18 to 24 hours. The starter may thus be
propagated from day to day. Occasionally, almost
pure cultures of lactic acid bacteria can be obtained
in this way, but this is an exceptional experience.
Results much more reliable come from the use of
commercial starters. (2) Commercial starters. — Com-
mercial starters are special preparations consisting of
certain organisms that produce lactic acid. These are
carefully prepared under the supervision of trained
bacteriologists and sold to cheese-makers. They are
usually known as cultures or pure cultures. The
medium in which these organisms are sent out may
be milk, broths, milk-sugar or porous paper. Proper
directions, with necessary precautions, usually ac-
company these commercial preparations. Below is
given a satisfactory method for the use of a com-
mercial preparation in making a starter for cheese-
making.

Inoculation of the culture. — In a can or glass ves-
sel that has been thoroughly cleaned and sterilized
with boiling water, place one quart of clean, sweet
milk. Heat the milk to at least 185° F. for one hour
by placing the can or vessel in boiling water. At the
end of an hour cool the milk rapidly to 95° F. by
setting the can or vessel in cold water. Then add the
contents of the small bottle of a prepared culture to
the milk, stirring it in with a sterilized spoon. Allow
the milk to cool gradually to 70° F. and hold at this
temperature for 24 hours. At the end of this time
the milk should be sour and coagulated.

20 SCIENCE AND PRACTICE OF CHEESE-MAKING

Propagation of starter. — In a can that has been
thoroughly cleaned and sterilized, place two gallons of
clean, fresh skim-milk. Heat the milk to 185° F. for
one hour by setting the can in boiling water. Stir
the milk frequently to insure even heating. After the
milk has been held at this temperature for one hour,
it may be cooled immediately to 70° F. by placing
the can in cold water. Then add the contents of the
small vessel that was prepared on the previous day,
stirring it in with a sterilized spoon. Hold the tem-

FIG. 6 — THIS STYLE OF DIPPER HAS A SOLID HANDLE
AND IS EASY TO KEEP CLEAN IN EVERY PART

perature at 70° F. for 18 hours. At the end of this
period the milk should be sour and firmly coagulated.
A uniform starter can thus be prepared from day to
day, always adding enough of the coagulated starter
to the amount of pasteurized skim-milk necessary for
the cheese-making process.

Precautions. — All vessels, pails, dippers, thermome-
ters and everything with which the starter-milk comes
in contact should be sterilized before being used.
Starters should not be prepared from the milk mixed
in the vat or from whey. A good starter is an in-
valuable aid in cheese-making, while a bad one is a
sure source of trouble. As soon as the starter loses

FIRST STEPS IN CHEESE-MAKING 21

its clean, nutty, mild aroma and sharp taste, it should
be replaced by a new one.

Use of starter in cheese-making. — The amount of
starter that can safely be used will depend on the
amount of acidity or ripeness of the milk at the start.
Generally, from 0.5 to 2 per cent is sufficient, but, if
the milk is very sweet, as much as 5 per cent can
be used. In using- a starter, reject the upper portion
and pass the rest into the milk through a fine strainer.
If colored cheese is being made, add the starter before
the color; otherwise white spots in the curd may be
produced.

Finding proper degree of ripeness. — The proper
degree of ripeness can be ascertained by the following
methods : • -

(i) By the use of the test for acidity (p. 4^6) ; ^^^^^^^^r

(2) by the use of the Marschall rennet-test (p. 429) ; c/

(3) by the use of the Monrad rennet-test (p. 431).

The general aim of ripening is to have such a degree
of acidity when the rennet is added that the. curd will
remain in the whey not more than 2^ to 3 hours.
This time will vary with the seasons of the year, the
important point being to have the curd firmed in the
whey before too much acidity has developed. Usually
when the acid test shows 0^19 to 0.21 per cent of
acidity, or when the milk coagulates at 2^ spaces in
the Marschall rennet-test, or in 45 to 60 seconds by
the Monrad test, the proper degree of ripeness has
been reached. Milk testing over 0.21 per cent acidity
when delivered at the factory is generally overripe and
Hable to cause trouble ; therefore, it should not be ac-
cepted, unless most of the other milk delivered at
the time has considerably less acidity.

22 SCIENCE AND PRACTICE OF CHEESE-MAKING

ADDING COLOR

When coloring--matter is used, it should be added
just before the rennet, being diluted before addition
and thoroughly mixed through the mass of milk. The
amount used depends on the demands of different
markets. About i ounce for i,ooo pounds of milk is

"^ generally sufficient, but the amount may vary from

I Yz ounce to 3 ounces.

PREPARATION AND ADDITION OF
RENNET-EXTRACT

^ Adding rennet-extract is commonly known as

"setting" milk with rennet. As soon as the milk is
^ - — .
^,*^ ripe enough the rennet-extract should be added. In

the use of rennet, three points must be kept in mind:
(i) Temperature of milk; (2) amount of rennet-
extract to use; (3) method of adding rennet-extract
and thorough stirring after addition.

(i) Temperature of the milk. — The ideal tem-
perature, under normal conditions, is 86° F., al-
though many successful cheese-makers prefer a
<^ ^3/" temperature of 84° F. At higher temperatures
^^/i»,.*<^^ the curd hardens too quickly to handle conven-
iently, and there is danger of loss of fat later in the
cutting. Lower temperatures require a longer time
for a proper degree of hardness, and, if the extra
time is not allowed, give too soft a curd, which
results in loss in cheese yield. The temperature
should be uniform throughout the milk.

(2) Amount of rennet-extract to use. — This will
depend on (i) the strength of the extract, (2) the

FIRST STEPS IN CHEESE-MAKING 23

temperature of the milk, (3) the acidity of the milk,

(4) the composition of the milk, (5) the kind of

cheese to be made, and (6) the temperature of

curing (p. 61). In general, an amount sufficient

to coagulate the milk fit for cutting in 25 to 35 - J J'- /r

minutes should be used. Generally from 2}4 to 4

ounces for 1,000 pounds of milk will suffice.

(3) Method of adding rennet-extract and subse-
quent treatment. — Before being added to milk, the
rennet should be diluted with 40 times its volume ^ ,
of pure, cold water. The object of this is to enable
one to distribute the rennet solution thoroughly
and uniformly throughout the mass of milk before
the rennet begins to coagulate the casein. Rcnne.t
acts more slowly when diluted with cold water
(p. 307). The milk should be thoroughly stirred
before the rennet is added. The diluted rennet
should be gradually poured the whole length of
the vat, and the milk at once stirred again for 3
to 5 minutes. A rake may be used to advantage
for stirring. Then the surface is stirred gently to
keep the cream from rising. All motion of the
milk should be stopped as soon as, or before, coag-
ulation starts. The vat should be covered to pre-
vent cooling at the surface and to keep out flies
and dust, and then left undisturbed until ready for
cutting.

Causes of imperfect coagulation. — By imperfect
coagulation, we mean (i) incomplete or delayed
coagulation of casein, shown by slimy or gelatin-
ous appearance of the coagulated milk and a curd
containing too much whey; or (2) variation In de-
gree of hardness in different portions of the mass

24 SCIENCE AND PRACTICE OF CHEESE-MAKING

of milk, some portions being too hard and others
too soft. Imperfect coagulation results (i) in ex-
cessive loss of fat and of casein from the soft curd and
(2) in imperfect texture and body in cheese, due to
the hard pieces of curd.

The causes of imperfect coagulation may be:

(1) For incomplete or delayed coagulation:

(a) Jarring of milk after coagulation starts.

(b) Weak rennet-extract or too small an amount.

(d) The presence of formalin (p. 308).

(e) Abnormal milk, containing small percentage 01
casein or small percentage of calcium salts (p. 164).

(f) Pasteurized milk (p. 310).

(g) Presence of abnormal bacterial ferments,
(h) Heavily watered milk (p. 307).

(i) Use of badly rusted milk-cans (p. 309).

(2) For uneven coagulation:

(a) Uneven temperature of milk in vat, due to lack of
thorough agitation.

(b) Adding rennet to milk too soon after heating, while
the sides and bottom of the vat are still hot. The curd sticks
to the sides of the vat and makes cutting difficult.

(d) Uneven distribution of rennet -extract.

CHAPTER III

Operations from Cutting Curd to Salting

CUTTING THE CURD

Purpose of cutting curd. — The object of cutting
curd is to allow the whey to escape from it. The
rapidity of the escape of whey increases with the
smallness of the pieces of curd.

When to cut curd. — Curd must be cut at the
right stage oi hardness. The stage for cutting is
ascertained in several ways. We give three of
them, (i) The end of the index finger is inserted
obliquely into curd half an inch or more and then
slowly raised to surface. If the curd breaks apart
with a clean fracture without leaving small bits
of curd on the finger, and if the whey in the broken
surface is clean and not milky, the curd is ready
to cut. (2) Lay the back of the hand, including
the fingers, on the surface of the curd near the
edge of the vat and press it gently away from the
side of the vat. As soon as it will separate from
the side of the vat in a clean way, leaving no par-
ticles of curd on the side of the vat, it is ready to
cut. (3) The following is probably the most ac-
curate rule for determining when the curd should
be cut : Tzvo and one-half times the period from add-
ing rennet til! the first thickening appears gives the
time for cutting.

26 SCIENCE AND PRACTICE OF CH.7.ESE-MAKING

Example:

Time when rennet was added, 7 130 a. m.
Time of first thickening, 7 140 a. m.
From adding rennet till first thickening=io min-
uteSo

.25^ times 10 minutes=25 minutes,

7:30+25-=7:55. ^

Time of cutting is 7:55 A. m.

When curd is cut too soon, the loss of fdt, and
probably of casein, is increased and there is a
smaller yield of cheese. If the curd becomes too
hard, it cannot be cut uniformly; if a wire knife
is then used, the wires may break.

How to cut curd. — Uniformity in the size of
pieces is the aim of good cutting. This can be
most easily accomplished by cutting slowly length-
wise of the vat with a %-inch steel horizontal
knife having sharp edges. Then cut crosswise
with a 5-16-inch perpendicular, wire knife. Finally,
cut lengthwise with the same wire knife. Care
should be taken not to smash the curd when insert-
ing the knives or when turning them at the ends
of the vat. The resulting cubes should be of uni-
form size to insure an even escape of whey, a
well-regulated development of acidity in curd and a
uniform color in the cheese. Extra losses of cheese
constituents (p. 193) In the whey are due to care-
lessness or lack of skill in the cutting or in the sub-
sequent stirring. The knives should be drawn
straight and even and should not overlap the por-
tions previously cut. The faster the cutting, the
smaller and more uneven the cubes will be.

CUTTING CURD TO SALTING 27

Effect of cutting curd fine or coarse. — The effect
of cutting curd fine is to release the whey more
rapidly and completely and to produce a cheese
containing less moisture. This fact is made use
of in the handling of overripe milk (p. 122) ; the
quick escape of whey enables one to control better
the acidity in the curd. Curd must be heated to
a certain temperature for a certain length of time
before it becomes firm enough to insure good body
in the cheese. If the pieces of curd are larger,
it takes longer for the whey to escape and longer
for the pieces to contract and become firm. Con-
sequently, if knives that cut coarser are used, the
rennet must be added when the milk shows less
acidity, in order to allow the curd to remain in the
whey a longer time.

Behavior of curd after being cut. — After the curd
is cut into small cubes, a slight coating or film
begins to form on the outer surface of each cube.
The existence of this film can be shown by break-
ing one of the curd cubes; the film can then be
seen. The inner portion of the curd is observed
to be softer^ due to the larger amount of whey
present. It is important that this film should not
thicken or harden too rapidly and thus prevent
the escape of whey in desired amount. The sub-
sequent operations have for one of their important
objects control of the expulsion of whey and simul-
taneous hardening or contracting of the pieces of
curd. The contraction or hardening of the pieces
of curd is known as "firming." It is probably due
primarily to escape of whey. What share tem-
perature, rennet and acidity each has in the process
cannot now be stated definitely.

28 SCIENCE AND PRACTICE OF CHEESE-MAKING

STIRRING CURD AFTER CUTTING

If the curd is not stirred immediately after cut-
ting, it soon masses together or becomes kimpy.
To prevent this, the curd must be kept in motion
till the pieces become properly firmed. Th.e stir-
ring of the soft, tender curd should be very gentle
at first and should be done with an agitator (Fig.
7). In large factories, steam-power agitators are
used. After the pieces of curd become healed over
on the surface by the formation of the film de-

FIG. 7 — MCPHERSON HAND-AGITATOR FOR STIRRING
CURD IMMEDIATELY AFTER CUTTING

scribed above and start to contract, they can be
stirred and kept separated more easily by using a
wooden rake (Fig. 8). The curd should be pre-
vented from collecting in the corners of the vat and
from sticking to the sides. Rough handling of the
soft curd crushes it and causes a severe decrease in
the yield of cheese, as the result of increased loss of
cheese-solids in the whev.

CUTTING CURD TO SALTING 29

HEATING THE CURD

When to apply heat. — The rapidity with which
the pieces of curd contract and the rapidity with
which the lactic acid is being formed determine
the time at which the heat should be applied. In ^^^^
any case, the curd should be stirred gently for -^
some time after cutting, until the small pieces have
healed over, or formed a film, and have contracted
slightly. Heat alone does not firm the curd. It
is probably due to the combined action of heat, ren-

FIG. 8 — DOUBLE-TOOTHED CURD-RAKE USED FOR
STIRRING CURD AFTER CUTTING

net and acidity. The firming and contraction of
curd and expulsion of whey go on together. The
faster the acidity is increased, the quicker will the
curd contract. The action of heat in the process of
contraction enables the curd to retain its firmness
and also prevents the reabsorption of whey.

How high to heat curd. — The lower the tempera-
ture used for heating curd, provided the curd be
properly firmed, the smoother^ will be the body of
the cheese. As a rule, 98° tc i(X)° F. will be high

30 SCIENCE AND PRACTICE OF CHEESE-MAKING

enough, but this can be varied from 96° F. in the
springtime to 102° F. in the fall. Curd from milk
rich in fat is harder to firm than curd from poor
milk, owing generally to the smaller proportion
of casein relative to fat. Thus, milk containing
3 to 3.6 per cent of fat ordinarily behaves at 94° to
96° F. the same as milk with 4 to 5 per cent of fat
does at 98° to 102° F. In extreme cases, the
temperature may have to be raised even higher to
firm successfully the curd from overripe milk. High
heating generally causes a corky or rubberv-bodied
cheese.

How to regulate heat. — Care must always be
taken not to raise the temperature of the curd too
rapidly. Usually the temperature can be raised
about 2° F. in every 5 minutes, but when the lactic
acid formation is slow, 1° F. every 5 minutes may
be sufficient. The following rule is a reliable guide
in heating:

Rule for heating. — If, after cutting, the whey
around the curd shows 0.12 per cent acidity, allow
60 minutes for heating; 0.13 per cent acidity, al-
low 40 minutes for heating; 0.14 per cent acidity,
allow 30 minutes for heating; 0.145 per cent acidity,
allow 25 minutes for heating; 0.15 per cent acidity,
allow 20 minutes for heating.

It is noticeable that the whey at this stage con-
tains 0.05 to 0.08 per cent less of acidity than the
milk does when the rennet is added. This is due
to the fact that the whey contains no casein and the
casein in the milk has the power of acting like an
acid in neutralizing alkali.

CUTTIXG CURD TO SALTING 3 1

Applying heat too fast hardens the outside of the
curd and prevents the escape of whey. The acid
in the curd develops from the sugar present in the
whey within the curd and not from the whey out-
side of the curd^ so that, if too much whey is re-
tained in the curd, too much acidity develops and
an acid or sour cheese results.

WHEN TO REMOVE WHEY FROM CURD

How to ascertain. — Several indications show
when the whey should be removed from the curd,
(i) The pieces of curd should be contracted to
less than one-half their original size. (2) They
should be firm and rubber-like, or springy, so that
when a mass of curd is pressed between the hands
and then suddenly freed from pressure, the pieces
should fall apart at once and show no tendency to
stick together. (3) When firm, the curds should
show fine threads ^ inch long when rubbed on a
clean, hot iron (p. 438). (4) The whey around
the curd should have 0.16 to 0.18 per cent of acid-
ity, as shown by the acid test. This will vary
slightly, depending on the time required for re-
moving the whey. The quantity of milk in the vat,
the size of the outlet of the vat, and the condition
of the curd should govern the amount of acidity
developed at the time of starting to remove the
whey. It is a good practice to draw ofif the whey
down to the level of the curd in the vat a few min-
utes before sufficient acidity has developed. This
gives a better chance to control the remainder.
The most accurate rule to follow is to have 0.24

32 SCIENCE AND PRACTICE OF CHEESE-MAKING

to 0.30 per cent of acidity in the whey running
from the curd after it has been stirred dry enough
and piled up for cheddaring. The amount of acidity
developed will depend on the character of cheese
desired and upon the amount of moisture left in the
curd. A firm export cheese requires more acidity
and less moisture than a quick-ripening cheese for
home trade.

STIRRING CURD TO DRY IT

The proper place to stir and to dry the curd is
in the whey, from the time the whey has reached
the curd level until it is all removed. This gives
a brighter and better color to the curd and re-
quires less labor than when stirring is delayed
until all whey has been removed. If the curd is
not properly firmed, vigorous hand-stirring may
cause serious loss of fat here. Too much free whey
should not be left around or in the pieces of curd
at this time, as it enables lactic acid to develop too
fast, owing to the presence of the milk-sugar in the
whey (p. 45).

CHEDDARING THE CURD

This operation is the main distinctive feature of
the cheddar method of cheese-making. It consists
essentially of two operations or a continuation of
one operation in two stages : ( i ) Piling or matting
of curd and (2) cutting curd into strips and con-
tinuing the operation of piling and repiling.

Piling or matting curd. — As soon as the curd has
been stirred enough to become sufficiently dry, it

CUTTING CURD TO SALTING 33

should be piled evenly along the two sides of the
vat, with an open channel 4 to 6 inches wide be-
tween the piles, to facilitate the ready drainage of
the whey that comes from the curd. The vat should
have dip enough to enable the escaping whey to
pass away rapidly and keep it from lying in pools
around the curd. Up to this time the curd should
not have been allowed to become lumpy, but, as
far as possible, the small pieces should be kept
separated. This results in a more uniform expul-
sion of whey, a more uniform development of acid
and a more uniform color in the curd. Some
cheese-makers use curd-sinks to dry the curd in
during this stage. Others use strainer-racks on the
bottom of the vats. In using these, the curd and
whey are dipped in pails on to the racks, which are
covered with cheese-cloth. The whey drains
through the racks and the curd is easy to stir. The
curd-sinks and vat-racks are of some aid in han-
dling curd from overripe milk, but under normal
conditions they have no particular advantage over
the vat.

Cutting and repiling curd. — As soon as the curd
has become matted together sufficiently, forming
a solid mass about 6 inches deep, it should be cut
into blocks or strips 6 to 8 inches wide and turned
over, the top going on the bottom. This takes 15
to 20 minutes from the time of piling. If the curd
contains excessive amounts of visible or free whey,
the blocks should be cut very narrow and turned
as soon as matted. After draining about 15 min-
utes, the strips are piled in layers two deep, each
time the upper part being turned down. The blocks

34 SCIENCE AND PRACTICE OF CHEESE-MAKING

are then turned every 15 minutes until the opera^
tion is completed. After a while the strips may be
piled in deeper layers. The repiling is performed
again and again, always exposing to the air the
portions that were turned inside on the previous
piling, in order to keep the temperature uniform
through the mass. The operation is hastened by
piling the strips two or three layers deep. If the
curd is very moist and the formation of acid goes
on quickly, it is not advisable to pile the blocks in
deep layers. It is better to separate them so that
they will dry out as soon as possible.

Object of cheddaring operation. — The object of
the cheddaring operation is to accomplish two re-
sults : ( I ) The formation of a curd containing less
water by the removal of whey; and (2) the forma-
tion of a characteristic body and texture in the
curd. The physical condition of the curd changes
from a tough, rubber-like consistency with a high
water content to a mass having a smooth, velvety
appearance and feeling, and a softer, somewhat
plastic consistency. The texture also changes so
that the curd acquires a peculiar fibrous condition
or grain, tearing off somewhat like the cooked
meat of a chicken's breast. Along with these
changes the curd forms longer strings on a hot
iron, usually an inch or more after the cheddaring
has continued for some time. Some chemical
changes appear to take place in the proteins. The
changes noted above are due to the formation of a
substance in the curd which is dissolved in warm,
5 per cent brine (p. 147). This substance in pure

CUTTING CURD TO SALTING 35

condition forms very long strings when warm.
(Figs. 32 and 33, p. 148.)
Completion of the cheddaring process. — The

cheddaring process is regarded as complete when
we have the following conditions : ( i ) The curd
forms strings on a hot iron an inch to an inch and
a half in length. (2) The whey running from the
curd shows an acidity of 0.65 to 0.90 per cent, de-
pending on the whey content of the curd and the
manner in which it is cheddared. (3) The curd
should be velvety in appearance and feeling, and tear
apart like the breast-meat of a chicken.

MILLING CURD

When the cheddaring process is complete, as
determined by the tests given, the curd is ready to
mill. The objects of milling are to cut the curd
into small pieces of uniform size^ in order that the
curd may be salted more evenly and handled more
easily in salting during the rest of the cheese-
making process; and also to permit the escape of
more whey. In cheddaring the curd, it should be
piled so that, when ready, the strips will be in
convenient shape and size for milling. The mill
should cut the curd into small pieces of uniform
size, and should do it without crushing or squeez-
ing the milk-fat from the curd. If a steam-power
curd-mill is used, it should not be run too rapidly,
for it will cut the curd unevenly and the texture
of the cheese will be poor. After milling, the pieces
of curd should be well stirred, kept apart, and freely
exposed to fresh air. At this stage the freshly cut
surfaces afford an excellent channel for the escape

36 SCIENCE AND PRACTICE OF CHEESE-MAKING

of gases and undesirable flavors. The airing and
stirring are made easy by the use of forks.

After mining, the curd is piled up in order to
flatten out pin-holes, if any, and stirred enough to
keep it from matting together. The softening of
the curd continues after milling, along with the fur-
ther formation of lactic acid. The curd should be
kept warm all the time.

If the operations up to this time have been prop-
erly managed, the whey remaining in the curd has
become a part of it to such an extent that not a
drop can be squeezed by pressure of the curd in
the hand. If, however, the whey has not become
perfectly incorporated with the curd-solids, more or
less free or unassimilated whey is found inside the
original, small pieces of curd ; and, when these are
broken in the milling, white whey runs out of the
curd, involving considerable loss of fat.

CHAPTER IV

Operations from Salting Curd to Removal

from Press

SALTING CURD

When to apply salt. — After the pieces of curd
have become well contracted and feel silky and
mellow, they are ready to be salted. The curd at
this stag-e should show by the hot-iron test strings
i^ inches long-, but this test cannot be relied upon,
as most curds become more or less greasy after mill-
ing, and do not so easily stick to a hot surface. A
test of the whey exuding from the curd is much
more reliable. It should have 0.90 to 1.2 per cent
of acidity, as shown by the acid test. This is the
most reliable test for indicating when curd is ready
for salting, and it is equally useful at other stages;
but students and cheese-makers should be familiar
with the use of all tests.

It is often a difficult matter to tell just when a
curd is in the best condition for salting, and this
knowledge comes only as the result of long expe-
rience. Generally, the curd smells like toasted cheese
when rubbed on a hot iron; and, when squeezed be-
tween the hands, a certain amount of fat may start,
but these tests are not reliable. The per cent of
acidity allowed to develop before salting depends
on the condition of the curd and also the conditions
of temperature and moisture under which the cheese

SCIENCE AND PRACTICE OF CHEESE-MAKING

is to be stored and ripened. If the cheese is to be
kept for any length of time in a warm room, the de-
velopment of acidity should be greater and the curd
matured more. This is especially true if the curd
is gassy or weak-bodied. If the curd is free from
gas, and the cheese is to be kept in cold storage till
ready for consumption, the acidity need not be so
great ; but, in any case, it should be sufficient to insure
a mellow body in the cheese.

Amount and kind of salt to use. — The amount of
salt used depends on (i) the amount of whey in the
curd, (2) its acidity, and (3) the type of cheese
desired. For ordinary factory milk, from i)4 to 2^^
pounds of salt for 1,000 pounds of milk used will
be sufficient, but in extreme cases these limits
may be exceeded. A moist curd is usually salted
more. The weight of milk, however, is not an ac-
curate basis for determining the amount of salt to
use. It is much better to use the weight of curd
or the percentage of fat in milk as indicated below.
Assuming that curd ready for salting contains

Per cent of

From 1 ,000 pounds of milk
Pounds of milled curd con-

Amount of salt to use

fat in milk

taining 40 per cent of water

Lbs. ~

Uzs.

3.0

87.4

3.1

89.8

13i

3.2

92.2

3.3

94.6

3.4

97.0

3.5

99.4

3.6

101.8

3.7

104.2

3.8

106.6

3.9

109.0

4.0

111.4

4.1

113.8

12^

4.2

116.2

4.3

118.6

15^

4.4

121.0

4.5

123.4

SALTING TO TAKING FROM PRESS 39

about 40 per cent of water, i,ooo pounds of milk
would furnish about the amounts of curd for the dif-
ferent percentages of fat in milk shown on page 38.

Salt of fairly coarse grain is preferable, because
it dissolves more slowly and penetrates the curd
more thoroughly. Special brands of cheese salt are
prepared by manufacturers and are generally shipped
in paper-lined barrels.

How to apply salt. — The curd should be spread
out thinly over the bottom of the vat, and, if neces-
sary, cooled to 90° F. Both curd and salt should
be free from lumps. The salt should be put on in
at least three applications, and each time should
be evenly distributed over the surface. After each
sprinkling of salt, the curd should be well stirred
with forks. Applying salt too rapidly or all at once
hardens the outside of the small pieces of curd and
hinders its absorption. A fine hair or copper sieve
is of considerable aid in regulating the application
of salt. Salt in cheese affects flavor, body, texture
and keeping quality (p. 343).

Effects of salting. — While salt is added mainly
for the sake of the taste it gives to cheese, it pro-
duces other effects, such as (i) aiding in removal of
whey; (2) hardening and contracting the curd;
(3) checking or retarding the formation of lactic
acid; and (4) checking undesirable forms of fer-
mentation. An unsalted cheese cures more rapidly
and is apt to develop a bitter flavor, the intensity
increasing with increase of ripening temperature.
Excessive salting makes a cheese mealy, because
too dry, and it cures slowly. Much of the salt
added passes into the whey. Green cheese normally

40 SCIENCE AND PRACTICE OF CHEESE-MAKING

salted contains 0.6 to i per cent of salt, and this
increases somewhat in the ripened cheese, through
loss of moisture (p. 344).

An increased quantity of salt is of advantage in
correcting such defects as gassy, highly acid, or very
soft cheese. Excessive loss of fat may often be
avoided by the early addition of salt, which hardens
the surface of the pieces of curd and prevents further
exudation of fat.

PRESSING CURD AND DRESSING CHEESE

Condition and temperature of curd when ready
for press. — Before the curd is placed in the hoops,
the salt should be completely dissolved ; the curd
should feel mellow and silky. No fixed pressing
temperature can be prescribed even for normal
curd, since there are several variable factors which
we must take into consideration. We can say that,
in general, under ordinary, normal conditions, the
temperature should be not much above 80° F., with
a range of variation from 78° to 85° F., according to
certain conditions, among the most important of
which are the following: (i) Size of cheese made;
(2) temperature of room; (3) condition of curd;
and (4) rate at which pressure is applied. Small-
sized cheese, such as Young Americas, Prints and
Picnics, should be put in press warmer than larger-
sized cheese, since they cool more rapidly. During
early spring, late fall, and winter months, the press-
ing temperature should be higher than during the
summer months. During the hot weather of sum-
mer, it may be necessary to cool the curd before

SALTING AND TAKING FROM PRESS 4I

pressing, which can be done by running cold water
around the outside of the vat, or by placing the curd
'in a cold room for a short time. One can usually
allow a somewhat wider range in the pressing tem-
perature when handling a normal curd than in the
case of one which is noticeably defective, such as a
greasy or a harsh curd. The faster a curd is put
into the hoop and pressed, the lower the temperature
it may be permitted to have.

The effects of pressing at too high a temperature
are the following: (i) Excessive loss of fat and
consequent loss of yield; (2) the pieces of curd be-
come greasy on the outside and do not stick to-
gether perfectly, which results in producing cheese
of less close texture on account of the increased
number and size of the mechanical-holes; (3) greasy
curd prevents bandage sticking to cheese; (4) high
temperature favors development of gas and conse-
quent huffing; (5) the loss of fat has the same
effect as skimming milk, as it makes the cheese too
dry.

The effects of pressing at too low temperature are
the following: (i) The pieces of curd do not stick
together perfectly, resulting in cheese of open texture
and imperfect rind formation, which affords an op-
portunity for entrance of mold and skippers; (2) it
may sometimes cause a mottled appearance when a
sample is drawn by a cheese-trier; (3) the cheese
retains more whey. '"''

Object of pressing curd. — The object of pressing
curd is to give the cheese a convenient form for
handling and a definite, characteristic shape for
market, and not alone to squeeze out whey, which

42 SCIENCE AND PRACTICE OF CHEESE-MAKING

should be removed mostly while the curd is in the
vat. Pressing will not make a close-textured cheese,
if the curd is gassy or too sweet. If the cheese is
to be close in texture, the curd must be full matured
before salting.

Preparing hoop for receiving curd. — A round cot-
ton cap-cloth of the size of the hoop is wrung out
of hot water and placed in the bottom of the hoop.
The bandage is then placed in the hoop, with
the edge turned in evenly about one inch on
the bottom. The curd is weighed in order to in-
sure a uniform size of cheese and is then put into
the hoop. The hoops should not be filled too full,
since the curd will be squeezed out around the top
when pressed. A cotton cap-cloth is then placed
over the top of the curd, and then the ring and
follower. Steel rings and followers are preferable
to fibrous rings and wooden followers. They are
more sanitary, easier to clean, are not absorbent, and
do not contract or expand easily.,

Applying pressure. — ^When the curd is put in
press in normal condition, a moderate pressure will
cause the pieces of curd to cement together in a
smooth, solid mass. The pressure should be uni-
form and continuous for 24 hours. With a screw-
press, the pressure is applied lightly and gradually
at first, full pressure being reached in about 15
minutes, and the press is tightened as fast as the
screws become loose, especially during the first
hour. After the curd has been in the press 45 to 60
minutes, it should be firmly cemented and ready for
dressing.

SALTING TO TAKING FROM PRESS 43

Dressing cheese. — Too much care cannot be taken
in finishing a cheese for market. The appearance
greatly influences an intending purchaser. As soon
as the cheese is sufficiently pressed, it is taken from
the hoop and placed on a dressing-bench. The
bandage is pulled up, made free from wrinkles, and
trimmed to about one inch on each end with a sharp
knife. A starched cap-cloth is placed on each end,
outside the bandage. Over these, the cotton cloths
are placed, and the cheese is then returned to the
hoop, where it is left until the following morning.
The cheese should then be taken from the press
and examined for imperfections in finish ; if any are
present, they should be remedied and the cheese
then returned to the press until the hoops are re-
quired for use again. It is better to have the cheese
in the hoops under pressure for 48 hours than for
only 24.

Plenty of hot water and clean, soft press-cloths
should be used to insure a good rind on the cheese.
Some cheese-makers place a cotton cloth around
the entire side of the cheese. This improves the
rind and protects the surface from any dirt or rust
marks that may be on the hoops. Others do not
take the cheese from the hoops to dress them, but
place a starched cap-cloth In the hoop before adding
the curd. Then, in dressing, the bandage is pulled
up from the top and, after being trimmed, a starched
cloth is placed on the upper end. This method
causes a greater waste of bandage, but otherwise
is satisfactory. The mechanical manipulations in-
volved in preparing the hoops and dressing the
cheese can be properly learned only froiu actual
practice.

44 SCIENCE AND PRACTICE OF CHEESE-MAKING

SIZES OR STYLES OF AMERICAN CHED-
DAR CHEESE

American clieddar cheese has come to be put upon
the market in an increasing number of varieties or
styles in respect to size. The main difference in
most cases is simply one of shape or size. The fol-
lowing list includes the most common varieties that
appear in trade :

Name

1. Cheddar or Export

2. Flats or twins

3. Home-trade

4. Daisies

5. Young America

6. Longhorn

7. Picnic

8. Square

9. Print

Shape

Cylindrical

Approximate
Size

Rectangular

In. diam.
14-15
14-15
11-13
12-13
7-8
5

4-5
Various sizes
10 X 10x21

Approximate
Weight

Pounds
60-70
30-35
20-25
20
8-12
12
1-2

(3-

4 in

10 (marked

. thick)
in blocks

or prints)

CHAPTER V

Moisture and Acidity in Curd and Cheese :
Conditions, Effects and Control

The detailed operations of cheese-making have
for their primary object, in large measure, regula-
tion of the amount of water and degree of acidity
in the curd. So important is the control of these
factors in relation to the quality of cheese, that
sometimes, under abnormal conditions, as, for ex-
ample, in case of overripe milk, they can be regu-
lated only by sacrifice of some of the fat, and the
question of saving fat then becomes a matter of
secondary importance. Of such importance is a
knowledge of these factors and their relations to the
detailed operations of cheese-making that a special
chapter seems desirable, even though the treatment
involves some repetitions.

To a considerable extent, moisture and acidity
are closely associated. Water means whey, of
course, and the most important constituent of whey
is milk-sugar, the raw material used in making
lactic acid. The larger the percentage of water
or whey in curd or fresh cheese, the larger is the
amount of milk-sugar, and, therefore, the greater is
the degree of acidity that can be developed. The
relations of moisture can be better understood if
we keep in mind the connection between (i)
moisture, (2) whey, (3) milk-sugar and (4) acidity.

46 SCIENCE AND PRACTICE OF CHEESE-MAKING

CAUSES OF EXCESSIVE MOISTURE

Among the most common causes of excessive
water in curd and cheese are the following: (i)
Cutting curd coarse or when too hard; (2) insuffi-
cient heating of curd in whey; (3) heating too
rapidly, thus hardening the outside of the pieces
of curd and preventing escape of whey; (4) low
degree of acidity before removing whey, usually
associated with, or caused by, insufficient heating;

(5) allowing curd to lie in whey too long and re-
absorb whey; (6) insufficient stirring. of curd after
removal or partial removal of whey; (7) high
piling of curd; (8) prolonged maturing in cheddar-
ing operation and postponement of milling in case
of soft curd; (9) insufficient amount of salt; (10)
soaking curd in water previous to salting (p. 57).

CAUSES OF INSUFFICIENT MOISTURE

The following are common causes of insufficient
moisture in curd: (i) Cutting curd very fine; (2)
heating curd too long or at too high a tempera-
ture; (3) excessive stirring of curd when the whey
is removed; (4) too much salt; (5) excessive loss
of fat may cause curd or cheese to appear too dry';

(6) high temperature and low humidity in curing-
room.

EFFECTS OF EXCESSIVE AND OF DEFI-
CIENT MOISTURE

Among the more prominent effects to be noticed
in relation to water in cheese-cu^'i and cheese, we

MOISTURE AND ACIDITY IN CURD^ ETC. 47

mention the following: (i) Development of acid-
ity; (2) influence on body; (3) relation to texture;
(4) effect on flavor; (5) influence on keeping qual-
ity; and (6) relation to finish.

Moisture and acidity. — The introduction to this
chapter gives the cause for the close relation of
moisture in curd to the formation of acid. In
case of a zvet curd, characterized by much water
(whey), we have a greater amount of milk-sugar
ready to form an additional amount of acid ; and, if
the temperature and other conditions are favor-
able, acidity increases rapidly. In the case of a
dry curd, the acidity increases more slowly, because
there is less whey, which means less milk-sugar with
which to make acid.

Moisture and body. — Curd containing too much
moisture (whey) becomes soft and produces a soft,
weak-bodied cheese (p. 87), which in extreme
cases is sticky and pasty (p. 63). The soaking of
curd in water after milling causes the absorption
of 5 per cent of water, more or less, and usually
results in a poor body. Cheese containing too little
moisture becomes dry, mealy, crumbly, more or
less rubbery, tough and hard. Such cheese is in
no way attractive. When curd is too dry, the
maturing process takes place with some degree
of difficulty and the curd is slow to change into
the characteristic, mellow, smooth, meaty body that
is desired. This is due to the presence of too little
whey in the curd, that is, too Httle milk-sugar with
which to form acid.

Moisture and texture. — Excessive whey in curd
and cheese is apt to favor the production of holes.

48 SCIENCE AND PRACTICE OF CHEESE-MAKING

especially when exposed to high temperatures.
Under the combined conditions of such defects of
texture and the soft, pasty body characteristic of
such cheese, the cheese easily loses its shape, bul-
ging more or less ; this sometimes goes so far as to
cause the cheese to roll off the shelf.

Moisture and flavor. — Cheese made from curd
containing a large percentage of water (whey) is
apt to develop offensive flavors in ripening, espe-
cially when kept at temperatures above 65° F. In
some cases, excessive moisture results in sour or
acid cheese. Dry cheese develops, flavor slowly
and can stand a higher ripening temperature.

Moisture and keeping quality. — Cheese contain-
ing a large amount of moisture has poor keeping
quality, as already indicated above in connection with
flavor and texture, while the reverse is true of
dry cheese.

Moisture and finish. — Cheese containing too
much moisture loses its shape easily in hot
weather, when the temperature of the curing-
room can not be controlled. In such cheese, the
rind formation is usually poor and cap-cloths do not
stick well.

CONTROL OF MOISTURE IN CHEESE-
MAKING

We now give briefly the means to be used in
controlling moisture at different stages of cheese-
making.

(i) Cutting curd. — The finer the pieces into
which the curd is cut, the more easily does the

MOISTURE AND ACIDITY IN CURD, ETC. 49

whey escape ; the larger the pieces of curd, th<^
less rapid the escape of whey. Under the same
conditions of treatment, a coarse-cut curd retains
more whey than one fine-cut. When curd is cut
before it becomes hard the whey escapes more
easily than in the ,case of curd cut after it becomes
hard.

(2) Heating curd in whey. — When the tem-
perature of curd in wdiey is raised too rapidly, the
film on the outside of the pieces of curd is harder
and more impervious, which seriously interferes
with the escape of whey. If the temperature is
not raised sufficiently high, the whey does not
escape as completely as it should ; this is especially
the case when an insufficient degree of acidity is
developed. Therefore the curd in the whey should
be heated gradually (p. 30) and the temperature
raised to the degree called for by the existing con-
ditions (p. 29). For method of avoiding dry curd
see p. 121.

(3) Removal of whey. — The whey should be
removed promptly when the curd is properly firmed.
When allowed to lie in whey after reaching the
right condition, the curd may reabsorb whey, which
can be removed only with extreme difficulty and
usually with considerable loss of fat.

(4) Stirring of curd. — Curd should be freed from
whey and made properly dry by sufficient stirring
after removal of whey (p. 32). ■

(5) Cheddaring curd. — In case of wet curd, it
should not be piled too high in the operation of
cheddaring, since this results in retention of more
whey than when curd is cut fine and not piled

50 SCIENCE AND PRACTICE OF CHEESE-MAKING

at all. In the case of dry curds, pile higher, etc.,
(p. I2l). ^

(6) Milling curd. — Early milling of curd favors
the escape of whey and may be resorted to when
too much whey is present at this stage, especially
in the case of a soft curd. Dry curds should not be
milled early.

(7) Salting curd. — The amount of whey in
cheese can be controlled, to some extent, by the
amount of salt used. In case of excessive moisture
in curd at the time of salting, this, may be reduced
by using an increased amount of salt. In case of a
dry curd, less salt should be used (p. 121).

(8) Ripening process. — The amount of mois-
ture in cheese can be regulated to a considerable
extent by control of temperature and humidity in
the curing- room (p. 317). Covering cheese with a
layer of paraffin goes far in retaining water in cheese

(p. 319).

CAUSES OF EXCESSIVE ACIDITY

Among the common causes of excessive acidity
in curd and cheese are the following : ( i ) Taking
too much overripe milk from patrons; (2) ripen-
ing milk too much in vat before adding rennet ;
(3) use of too much starter; (4) too long contact
of curd with whey or too high temperature; (5)
any condition which favors the retention of too much
whey in curd and cheese (p. 116).

CAUSES OF INSUFFICIENT ACIDITY

The following are common causes of too low a
degree of acidity: (i) Insufficient ripening of

MOISTURE AND ACIDITY IN CURD, ETC. 5 1

milk before adding rennet; (2) low degree of tem-
perature in heating curd in whey: (3) removal of
whey too soon; (4) any condition that favors the
rapid removal of whey and the formation of an
excessively dry curd (p. 121).

EFFECTS OF EXCESSIVE AND DEFICIENT

ACIDITY

Among the more prominent effects to be no-
ticed in relation to acidity in curd and cheese, we
mention the following: (i) Influence on rennet
action; (2) relation to shrinking of curd; (3) ef-
fect on expulsion of whey; (4) influence on color
of cheese; (5) relation to body of cheese; (6) ef-
fect on texture of cheese; (7) influence on flavor
of cheese; (8) relation to keeping quality of
cheese; and (9) effect on finish or general appear-
ance.

Acidity and rennet action. — At the temperature
used in cheese-making, rennet-extract coagulates
milk-casein only when acids or acid salts are pres-
ent (p. 306). The greater the percentage of acidity,
up to certain limits, the more rapid is rennet
coagulation, other conditions being uniform (p.

307).

Acidity and contraction of curd. — The greater
the acidity of milk, the more rapid is the contrac-
tion of the curd, other conditions being uniform.
This is not the same as saying that the contraction
is caused by acidity ; acidity is probably one of two
or more causes, or it may be simply a necessary
condition for the continued action of rennet, tem-
perature being another important condition for the

52 SCIENCE AND PRACTICE OF CHEESE-MAKING

shrinking of curd. The knowledge of the relation
of acidity and temperature to contraction of curd
enables the cheese-maker to heat the curd in the
whey more rapidly, since, in the case of excessive
acidity at the start, he can increase with comparative
rapidity the temperature, without danger of harden-
ing the external film of the small pieces of curd and
so preventing further expulsion of whey.

Acidity and expulsion of whey. — The contrac-
tion of curd is closely associated with expulsion of
whey and the relation of acidity to the two actions
is practically the same.

Acidity and color of cheese. — Formation of too
great a degree of acidity bleaches the color in the
curd, making it pale when the action is even, and
mottled when the acidity is different in different
portions. This condition is generally caused by the
retention of too much milk-sugar (whey) in curd
and cheese.

Acidity and body of cheese. — Excessive acidity
produces imperfect body in cheese, making it
harsh, corky and mealy. A certain degree of acidity
is an essential condition, if not one of the causes,
of the formation of a smooth, firm, silky body.
Insufficient acidity may cause cheese to be weak-
bodied.

Acidity and texture. — Cheese made from curd
containing a small amount of acidity is often faulty
in texture. Among such defects are holes, usually
called ''sweet holes." Excessive acidity and cracks in
cheese are often associated.

Acidity and flavor. — The characteristic flavor of
cheddar cheese is not developed without a certain

MOISTURE AND ACIDITY IN CURD, ETC. 53

degree of acidity. Excessive acidity (whey) gives

the cheese a sour flavor. Insufficient acidity is apt

to be accompanied by a sickish flavor, unless the ,^

cheese is ripened with care at sufficiently low tern- '^^^*^^^'

perature.

Acidity and keeping quality. — It has been al-
ready stated (p. 18) that the presence of lactic
acid bacteria in milk and curd is essential to pre-
vent the development of undesirable forms of
fermentation, which may be present in the early
stages of cheese-making. The lactic acid thus
formed is the active material employed in doing this
sanitary work. Cheese wdth too little acidity usually
becomes defective in flavor in a comparatively short
time.

Acidity and finish. — Excessive acidity (whey)
causes formation of poor rind ; frequently the rind
cracks and leaks whey.

CONTROL OF ACIDITY IN CHEESE-
MAKING

Below we give in brief form the means to be used
in controlling acidity in the operations of cheese-
making.

(i) Producer's care of milk. — In order to re-
tard the too rapid growth of lactic acid bacteria
before milk is delivered at the cheese-factory, the
milk should be cooled at once after milking to 60°
F., or better to 50° F., and not allowed to get above
this temperature.

(2) Ripening milk. — In making sweet-curd
cheese, care must be taken not to ripen the milk

54 SCIENCE AND PRACTICE OF CHEESE-MAKING

too much^ a mistake too often made by cheese-
makers. Milk which is overripe, whether at the
time of deHvery or as the result of ripening after
delivery, is difficult to handle (p. 122). In the
methods often employed, much loss of fat is often
experienced in order not to sacrifice quality in cheese.
The use of commercial starters (p. 19) gives the most
reliable results in ripening milk.

(3) Control of whey. — The degree of acidity in
curd and cheese is primarily dependent upon the
amount of whey retained, and control of the amount
of whey really means control of acidity. The methods
for this have been given (p. 48).

(4) Amount of acid at different stages. — The
degree of acidity should be kept under careful con-
trol at each stage of the operations of cheese-
making, which is done by careful regulation of
temperature and the different prescribed manip-
ulations of the curd. There must be a careful ad-
justment of conditions in respect to (i) the
rapidity of formation and thickening of the nlm
around the pieces of curd, (2) the contraction of
the curd, (3) the expulsion of whey, and (4) the
degree of acidity.

CHAPTER VI

Modifications of Cheddar Process and
Miscellaneous Subjects

In describing and discussing in detail the various
operations involved in making American cheddar
cheese, it has seemed best to reserve for a special
chapter several subjects which are more or less
closely related to this method of cheese-making,
but which do not form an essential part of it. Of
the many topics which might come in this chapter,
the following have been selected for consideration :
(i) "Stirred-curd" method; (2) "soaked-curd"
method; (3) pasteurized milk in cheese-making;
(4) slow-ripening and quick-ripening cheese; (5)
home-trade cheese; (6) use of artificial acids in
cheddar cheese-making; (7) the use of pepsin in
cheddar cheese-making; (8) whey butter; (9) dis-
tribution and value of whey; (10) cheese poison;
(11) starters in relation to yield of cheese; (12)
making butter and cheese.

THE "STIRRED-CURD" OR "GRANULAR"
PROCESS OF CHEESE-MAKING

This process was exclusively used in America
for many years and is still in operation in some
cheese-factories. While it is not our purpose to
present a detailed description of this method, it is
desirable, as a matter of information, to state its

56 SCIENCE AND PRACTICE OF CHEESE-MAKING

most essential points, especially those in which it
differs from the cheddar method. The cheddar and
stirred-curd methods are identical until the time
comes for the removal of the whey from the curd,
when they differ in the following respects : ( i ) In
the cheddar process the whey is removed from the
curd when the hot-iron test shows strings ^ to ^
inch long; in the stirred-curd process, the curd re-
mains longer in the whey, until the hot-iron test
shows strings >^ to i inch long. (2) After the re-
moval of whey, the curd, in the cheddar process, is
packed and then cheddared; while, in the stirred-
curd process, the curd is transferred to a curd-sink
and is more or less frequently stirred, so that the
small pieces are kept separate; and at no time is
the curd permitted to pack in a solid mass. The
main object of keeping the curd longer in the whey
is to firm the curd to such an extent that it can be
kept in the ''granular" form more easily. (3) In the
cheddar process, the time between the removal of
whey and salting is much longer than in the stirred-
curd method; while (4) the time between salting
and pressing curd is much longer in the stirred-
curd process. These general differences are well

Method used

Time from reach-
ing 98° F. to re-
moving whey
from curd

Time from remov-
ing whey to salt-
ing curd

Time from salting

to pressing

curd

Cheddar

Stirred-curd

Cheddar

Stirred-curd ....

Cheddar

Stirred-curd ....

Minutes

90
175

62
100

90
164

Minutes
200

25
133

15
230

Mmutes

10
100

30
140

MISCELLANEOUS SUBJECTS 57

illustrated by the foregoing data, which were ob-
tained at the New York experiment station in mak-
ing different portions of the same milk into cheese
by these two methods.

It will be noticed that, in general, the total amount
of time consumed is about the same by either
method. The time is simply distributed differently
at certain stages of the work.

It is much more difficult with this method to
make cheese of perfect texture, at least considered
from the standpoint of the type of cheese intended
for export. It was the influence of the demands
of the English market which caused American
cheese-makers to change from the stirred-curd to
the cheddar method. The cheddar process has the
marked advantage of enabling the cheese-maker
to control his operations more completely and pro-
duce cheese of close texture. Greater skill is re-
quired to produce results by the stirred-curd method
equal to those obtained with the cheddar method.
Under ordinary conditions^ the stirred-curd method
produces cheese with a little higher content of mois-
ture, but not necessarily so. The loss of fat is the
same by either method.

THE "SOAKED-CURD" METHOD

This is a modification of the cheddar method,
which has for its object an increase of water other
than that derived from the whey. It is to be dis-
tinguished from the advantageous practice of wash-
ing curd in the case of abnormal flavor, excessive
acidity, etc. It is applied to both skim-milk and

55 SCIENCE AND PRACTICE OF CHEESE-MAKING

normal-milk cheese. The process is simply this:
When the curd has matured ready for salting, it is
covered with cold water and allowed to soak lo to
15 minutes. In this way the amount of water in
100 pounds of cheese can be increased ordinarily
4 or 5 pounds, producing a cheese with 41 to 44
per cent of water. The soaking of curd by this

FIG. 9

Showing the effect of excessive moisture in a soaked-curd cheese upon the
body. The cheese with normal moisture Iceeps its shape perfectly. The soaked-
curd cheese bulges at the sides and flattens down if kept at temperatures 65 or 70
degrees F.

process not only increases the yield of cheese by
the incorporation of water other than what was a
part of the original milk from which the cheese was
made, but it also dissolves from the curd (i) milk-
sugar; and (2) the soluble calcium salts, especially
acid calcium phosphate. These normal cheese con-
stituents, which are thus removed from the curd,
are essential to the normal ripening process of the

MISCELLANEOUS SUBJECTS 59

cheese and, in their absence, cheese undergoes ab-
normal fermentations as the result of the action of
putrefactive bacteria. These facts have been es-
tablished by work done at the Cornell University
experiment station. This practice has been de-
fended on the ground of removing undesirable "im-
purities" carried into the cheese by the whey. This
is a pure assumption which has no foundation in

FIG. 10

Showing the difference between the close texture of normal cheese and the
loose, spongy texture of a soaked-curd cheese.

fact. The whey-solids, thus miscalled ''impurities,"
are normal constituents of cheese and are necessary
to the completion of the ripening process when
present in normal amount. Cheese made by the
soaked-curd process is very properly not permitted
the use of the brand designed for whole-milk cheese
in New York state, on the following grounds : ( i )
Water other than that present in the original milk
from which the cheese was made is incorporated
with the cheese for the purpose of increasing its

60 SCIENCE AND PRACTICE OF CHEESE-MAKING

weight without improving its quaHty; and (2) the
soaking process removes normal constituents that are
essential to the ripening of the cheese. These grounds
are based upon established facts.

Cheese produced by the soaked-curd process
usually exhibits the defects characteristic of cheese
containing an excessive amount of moisture ; these
are weak body and loose texture (pp. 86-87). When
kept at temperatures above 65° or 70° F., such
cheese fails to stand up like normal cheese and it
also suffers in texture from the effects of gassy fer-
mentations. Figs. 9 and 10 well illustrate the truth
of these statements. They represent v/ork done at
the Cornell University experiment station with
cheese made according to the soaked-curd method.

CHEDDAR CHEESE FROM PASTEURIZED

MILK

Many attempts have been made to manufacture
cheddar cheese from pasteurized milk. The results
in America have not been wholly encouraging up to
the present time. The cheese is generally imperfect
in body, lacking in flavor and slow in ripening. We
do not, therefore, think it desirable to devote fur-
ther attention to the various modifications of details
required in its manufacture. It is said that much
skim-milk cheese is successfully made in Denmark
from pasteurized milk. -^-ttT'^*^ y^ ^ ^ /^^^^m-^^^^

CONDITIONS OF CHEESE-MAKING

PROCESS FOR QUICK-RIPENING

AND SLOW-RIPENING CHEESE

Certain conditions of the cheese-making process
promote, while others retard, the rapidity of ripen-

MISCELLANEOUS SUBJECTS 6l

ing. The general relation of different conditions to
the rapid or slow rate of cheese-ripening may be
shown by the following form of statement :

Conditions that may Conditions that may
promote ripening: retard ripening:

(i) Increase of ripening (i) Decrease of ripen-
temperature. ing temperature.

(2) Larger amount of (2) Smaller amount of

rennet. rennet.

(3) More moisture in (3) Less moisture in

cheese. cheese.

(4) Less salt. (4) More salt.

(5) Large size of (5) Small siz3 of cheese.

cheese.

(6) Moderate amount of (6) Deficient acidity or

acid. excess of acidity..

If a cheese is desired that ripens quickly, it
should contain more than the usual amount of ren-
net, a moisture content of about 40 per cent or
more, and about i to 13^ pounds of salt for 1,000
pounds of milk. Then it should be kept at a tem-
perature between 60° F. and 70° F., if it is to be
placed in the hands of consumers in one month or
six weeks, and the atmosphere of the curing-room
should have a humidity of 75 to 85 per cent of
saturation. However, it should be stated that
cheese made to ripen quickly gives better results
in commercial quality when ripened at a lower
temperature than 60° F. and held a longer
time.

For a slow-ripening cheese, not more than 2^
ounces of rennet-extract, such as Hansen's, should

62 SCIENCE AND PRACTICE OF CHEESE-MAKING

be used for 1,000 pounds of milk, and about 2 to 2^/^
pounds of salt. The other conditions that influence
the moisture content of cheese, such as the tem-
perature of heating- the curd, the fineness of cutting
curd, the amount of acid developed in the curd,
cheddaring, etc. (p. 45), should be well under
control, so as to produce a cheese containing, when
fresh from the press, about 37 per cent of water. For
ripening, it should be kept at a temperature below 50°
F. in a fairly moist atmosphere for a period of 3 to 6
months or more.

HOME-TRADE CHEESE

The majority of cheese consumers desire a cheese
soft in body and with a mild, clean flavor. Soft-
ness is synonymous with richness in cheese to
most people. While it is true that cheese rich in
fat possesses a characteristic softness, it is not true
that all soft cheese is rich in fat. The desire for a
mild-flavored cheese is a reaction from the taste
for a cheese of strong, pungent flavor. To meet in
the easiest way the demand for soft-bodied, mild-
flavored cheese^ there has arisen quite an extensive
manufacture of what is known as ''home-trade"
cheese. The method of making this kind of cheese
varies in its details in different localities, but the
general object is the production of a quick-curing
cheese which will be ready for consumption in four
to six weeks. The distinctive characteristics of
such cheese are its high water content, a conse-
quent softness of body and open texture, a mild
flavor when a few weeks old, and a poor-keeping
quality. These results are attained, in general, by

MISCELLANEOUS SUBJECTS 63

using large amounts of rennet-extract, developing
less acidity, heating the curd in the whey to 103°
to 110° F. and ripening at 60° to 70° F. In many
cases, where the conditions of ripening are not un-
der control, home-trade cheese is made only in the
fall, since there is less risk in handling the ripening
process at a time when the temperature is not high.
Home-trade cheese, when green, usually contains
38 to 40 per cent of water, but the percentage may
run up to 43 or even 45. The fact that this soft
cheese is more extensively made in the fall has led
cheese-makers to believe that ''milk very rich in fat,
such as strippers' milk, is liable to cause a pasty
cheese." Such a belief could hardly be further from
the truth, as shown by the facts given in Chapter
XV, pp. 164-167, where the influence of advancing
lactation on the composition of milk is discussed.

It should be stated in this connection that, in New
York state, a large proportion of the cheese made
under the name of home-trade is of a type, quite dif-
ferent from that described above. In the process
of making, the temperature is not allowed to go above
98° F. and the percentage of moisture is kept at 38
to 40. The resulting cheese is firm-bodied, close-tex-
tured and of good-keeping quality. It is the best
type of home-trade cheese and is in large demand.

USE OF ARTIFICIAL ACIDS IN CHEDDAR

CHEESE-MAKING

Attempts have been made to use artificial lactic
and other acids in making cheddar cheese, in order
to hasten the cheese-making operations. Theoreti-
cally, the addition of small amounts of dilute acid

64 SCIENCE AND PRACTICE OF CHEESE-MAKING

can take the place of starters in hastening tne ac-
tion of rennet, and, to some extent, in the subse-
quent stages. While it is possible to assist the lactic
acid bacteria in this way, great caution is required.
The addition of too much acid results in the produc-
tion of cheese that does not ripen. So far as w^
know, the application of artificial acids in cheddai
cheese-making has never been worked out to such
an extent that all details are under control. While
cheese of good quality can be made in this way, there
is probably no advantage, even when the process is
under absolute control ; and, in the absence of such
control, no one should ever attempt to employ such a
method in practical work.

USE OF PEPSIN IN CHEDDAR CHEESE-
MAKING

Commercial pepsin prepared from the stomachs
of sheep has been successfully used in place of ren-
net-extract in making cheddar cheese. The special
pepsin most used in this way is a scale-pepsin
known as 1-3000 strength. Five grams of this pep-
sin equal the coagulating power of 3 ounces of
Hansen's rennet-extract. The pepsin is dissolved
in cold water for use. In using pepsin, one should
make a solution and test it in comparison with ren-
net-extract on the same milk. (Modern Methods
of Testing Milk, etc., pp. 125-126.) Pepsin has the
following advantages over rennet-extract : ( i ) It
is more concentrated and, therefore, more conven-
ient and less expensive to ship. (2) If kept dry,
pepsin retains its strength indefinitely, while ren-
net-extract does not. These advantages of pepsin

MISCELLANEOUS SUBJECTS 65

over rennet-extract do not, of course, apply to ren-
net pozi'dcrs. The quality of cheese made by use of
pepsin does not appear to be inferior to that made
by the use of rennet. Commercial pepsin is probably
more expensive to use than rennet-extract and is not
uniform in strength.

MANUFACTURE OF WHEY-BUTTER

The fat in whey can be readily removed, in large
part, by means of a centrifugal separator, and the
resulting cream can be made into butter in much
the same manner as cream separated directly from
milk. The butter thus made is apt to be somewhat
softer than in case of normal butter ; the flavor is
fair to good. From the whey produced in making
io,(X)0 pounds of milk into cheese under normal con-
ditions, about 25 to 30 pounds of whey-butter can
be made under favorable conditions. This yield is
based upon an average loss of 0.3 pound of fat in
whey for 100 pounds of milk (p. 189). The removal
of milk-fat from whey does not greatly reduce its
feeding value.

The question of making whey-butter is largely a
matter of cost of production. In the case of small
cheese-factories, the yield of butter would not
repay the labor. In larger factories, it would be-
come, to some extent, a question of the amount
of fat in the whey. In general, it may be said
that the manufacture of whey-butter will be
usually found profitable under the following con-
ditions :

(i) When the daily average milk supply is not
less than 10,000 pounds and the amount of iat in

66 SCIENCE AND PRACTICE OF CHEESE-MAKING

whey averages 0.25 pound or more for 100 pounds of
milk.

(2) When the average cost of making whey-
butter can be kept sufficiently low. The usual cost
is 5 to 8 cents a pound, including cost of fuel, labor,
coloring-matter, salt, etc. Among the conditions that
favor economy of production are the following: (a)
A building so located and constructed that gravity
can be used to carry whey to and from the separator
at minimum cost; (b) a cheap supply of pure ice
and cold water; (c) the possession of a centrifugal
separator and a butter-making equipment as a part
of the factory plant; (d) reasonable cost of fuel and
labor.

(3) When a gooa quality of butter is made.
This, of course, requires pasteurization of cream, the
use of a good commercial starter, extreme cleanliness
at every stage of the butter-making process and proper
sanitary surroundings.

In St. Lawrence County, New York, several fac-
tories have formed a combination for the successful
manufacture of whey-butter. The separated cream is
sent by each to a central butter-making station. When
all conditions are favorable, a cheese-factory receiving
10,000 pounds of milk a day on the average, could
with profit install the equipment necessary for making
whey-butter.

DISTRIBUTION AND VALUE OF WHEY

The theoretical yield of whey for 100 pounds of
milk averages about 90 pounds, with a variation
between 87 and 91.5 pounds, according to the yield

MISCELLANEOUS SUBJECTS 67

of cheese for lOO pounds of milk. The theoretical
yield is reduced by the losses in the cheese-making
operations, due (i) to evaporation of water and
(2) to mechanical losses. The yield of whey varies
with the composition of the milk and, therefore,
with the time of season and other conditions that
affect the composition of milk (p. 204). In gen-
eral, it is safe to say that the yield of whey is about
88 pounds for 100 pounds of milk, taking the sea-
son as a whole ; but this yield is considerably
reduced by losses in handling. In allowing each
patron to take the portion of whey coming to him,
the usual amount is 80 to 85 pounds for 100 pounds
of milk delivered. Where the whey is valued by
every patron, it is essential that each one be as-
signed his just portion ; otherwise some will always
take more than belongs to them. There are various
satisfactory devices for controlling the amount of
whey each patron can take.

The chief value of whey to patrons is as material
for feeding pigs and calves in connection with
other foods. The feeding value of sweet whey
may be conservatively placed at 8 to 10 cents for
100 pounds. For the composition of whey, see
p. 197. Whey sours rapidly and loses a consider-
able amount of its milk-sugar under ordinary con-
ditions. In order that its highest food value may
be realized, it is essential that it should be pasteur-
ized promptly at 155° to 158" F. and the whey-vat
always kept in clean condition (p. 127). It is not prac-
ticable to sterilize whey, because the heat needed for
sterilization coagulates the albumin. Whey that is de-
cidedly sour often has an injurious effect on the animals

68 SCIENCE AND PRACTICE OF CHEESE-MAKING

to which it is fed, especially when fed alone and
in excess. There is another even more important
reason why whey should be pasteurized. The
whey-vat has been known to become a distributing
source of disease among calves and pigs and of ab-
normal fermentations that injure the quality of cheese.
Sweet whey has a value of 6 or 7 cents per 100 pounds
when sold for the manufacture of milk-sugar, but com-
paratively little whey can be actually disposed of in
this way.

CHEESE POISON

For a long time it was known that cheese some-
times acts as a violent poison, but it was not until
about 25 years ago that a specific poisonous com-
pound was isolated from cheese. Many cases of
cheese poisoning had occurred in Michigan at the
time and the matter was investigated by Dr. V. C.
Vaughan, professor of physiological chemistry at
the University of Michigan, who succeeded in sepa-
rating from some of the poisonous cheese an in-
tensely poisonous compound, which he called tyro-
toxicon (cheese poison). The poison is present in
cheese in only very minute amounts, but is intensely
powerful. A drop of a highly dilute solution of this
poison placed on the tongue produces a characteristic
benumbing sensation. This poison is the result of
bacterial action and is produced only by those bacteria
which are associated with conditions of filth. There
are sometimes also other poisons in cheese, less well
known.

MISCELLANEOUS SUBJECTS 69

STARTERS IN RELATION TO YIELD OF

CHEESE

When a cheese-maker uses comparatively large
amounts of starter, as 5 pounds for 100 pounds of
milk, the question arises as to whether this does
not increase the yield of cheese and is not practi-
cally equivalent to adding the same amount of
skim-milk. The amount of added casein thus intro-
duced is about 2 ounces and is equivalent to an
increased yield of cheese amounting to about 5
ounces for 100 pounds of milk. Theoretically, the
practice of adding large amounts of starter might
lead to abuse ; but rennet-extract does not act upon
the coagulated casein of sour milk or of buttermilk.
The casein contained in the starter, although held
fast in the coagulum at first, separates to a large
extent during the cheese-making in the form of
fine particles. When a large amount of starter is
used, these small particles are very noticeable in
the whey. The fact that the addition of a starter
to milk does not increase the yield of cheese has
been brought out by work done in the dairy de-
partment at the Cornell University experiment
station.

MAKING BUTTER AND CHEESE

The question is often raised as to whether or not
it pays to remove a part of the fat from milk and
make butter and part-skim cheese. As a rule, it
does not pay, unless one sells the part-skim cheese
for whole-milk cheese, and this is very difficult to
do now under our pure-food laws. The best advice

VO SCIENCE AND PRACTICE OF CHEESE-MAKING

that can be given is to make either butter or cheese,
but not to mix the manufacture of the two products.
Some cheese-factories drop cheese-making in the
fall and make butter during the winter. The rela-
tive price of cheese and butter will determine which
pays better. In general, it can be said that butter-
making pays better than cheese-making whenever the
price of butter is greater than two and one-third
times the price of cheese per pound. For example,
when cheese sells at lo cents a pound, butter-making
will pay better, if the price of butter is above 23 1-3
cents a pound.

CHAPTER VII

Care, Shipment and Sale of Cheese

It has been said that a cheese is really only half
made when it is taken from the press. This is, in a
great measure, true, because the conditions of tem-
perature and humidity to which a cheese is sub-
jected during the process of ripening or curing
largely determine its quality. An excellent cheese
may be absolutely spoiled by unfavorable ripening
conditions, while a cheese of inferior quality may
be much improved by being kept under favorable
conditions. The subject of cheese-ripening in its
practical relations is discussed in Chapter XXVI,

PP- 379-394-

CLEANING THE SURFACE

When each cheese is taken from the press, it should
be wiped off with a dry cloth, and any rust-spots or
finger-marks removed. Deep-seated spots of dirt can
be more easily removed by the use of a brush and hot
water.

PLACING CHEESE IN CURING-ROOM

No cheese should be placed in the curing-room
until it is clean and well finished. A badly finished
or dirty cheese never attracts a cheese buyer, in-
spector or consumer. Imperfections in quality are

^2 SCIENCE AND PRACTICE OF CHEESE-MAKING

often overlooked if the finish and general appearance
are good.

When cheese is placed in the curing-room, it
should be arranged in a neat manner upon clean
shelves or tables. Too many cheese-makers allow
the cheese-shelves to become moldy and dirty ; con-
sequently, when a clean cheese is placed on them the
end surfaces soon become stained and dirty. The
shelves should be thoroughly cleaned after each ship-
ment of cheese leaves the factory.

TURNING CHEESE DURING RIPENING

PROCESS

Each cheese should be turned on the shelf every
morning until ready for shipment. At the time of
turning, if an excess of moisture or any mold is
present, it should be wiped off with a dry cloth, or
with a damp one wrung out of a lo per cent solution
of formaldehyd.

MARKING DATE OF MANUFACTURE

When cheese is placed in the curing-room, the
date of its manufacture should be stamped on each,
so as to correspond with the number of the manufac-
turing record of the same date and thus avoid errors
in shipment.

USE OF CHEESE BRANDS

Many states have statutes providing for the
branding of cheese. The brand usually indicates
whethf?*" ^he cheese has been made from whole

CARE^ SHIPMENT AND SALE OF CHEESE 73

milk or skimmed milk. Brass stencils for this pur-
pose are usually sent to factories by the state de-
partments of agriculture, which keep a record of
the number of each factory, and this particular
number appears as part of the brand. This is to
protect the manufacturers of whole-milk cheese
from dishonest competition with those who remove
part or all of the fat from the milk before making
it into cheese. In Canada many factories stamp
the name of the factory on the cheese. In many
instances, this is a good plan, if the quality of the
cheese is good, but disastrous if the cheese is defec-
tive in quality.

WHEN CHEESE SHOULD BE SHIPPED

The age at which cheese should be shipped from
the factory depends on several conditions. If the
curing-room is one in which the temperature and
humidity cannot be controlled at all, the cheese
should be shipped within a few days to some place
where it can be kept under proper conditions. In
some places, central cold storages are located
where cheese, either before or after selling, is sent
to ripen. If the temperature in the cheese-factory
can be controlled, the cheese should not be shipped
so soon. Cheese lo days old is young enough, and,
if for export, two weeks will be much better. An
export cheese is not very palatable in less than one
month. A home-trade cheese containing a high
percentage of moisture may be ready at an earlier
date (p. 62)

During the past few years, complaints, in increas-
ing number, have been made by foreign cheese

74 SCIENCE AND PRACTICE OF CHEESE-MAKINC

merchants, who say that cheese is shipped to them
before it is old enough. The Canadian govern-
ment has lately been making vigorous efforts to
overcome this practice, which has become too com-
mon. The important point to be kept in mind is
that the cheese should be in an edible condition when
it reaches the consumer.

FIG. 11 — DAIRY STUDENTS WEIGHING, PARAFFINING AND BOXING

CHEESE

COVERING CHEESE WITH PARAFFIN

Loss of moisture in cheese can be largely pre-
vented by coating the cheese with a thin layer of
paraffin, and this can be done without injuring the
quality. The jiigher the temperature, the greater
is the prevention of loss. Another distinct advantage

CARE^ SHIPMENT AND SALE OF CHEESE

in using paraffin is that it prevents cheese becom
ing moldy. The cheese is allowed to dry well on
the surface and is then dipped for 8 to 15 seconds,
according to the size and temperature of the
cheese, in melted paraffin at a temperature of at

FIG. 12 — APPARATUS FOR PARAFFINING CHEESE

least 220^ F. Care must be taken to keep the par-
affin from acquiring a disagreeable odor as a result
of overheating. Cheese should be dry enough in
three to seven days to be ready for paraffining, but
the time will depend, of course, on the amount of
moisture in the cheese and in the curing-room. The
application of paraffin at a high temperature gives
a thin coating that adheres tenaciously and de-
stroys mold formation. If the temperature is too

y6 SCIENCE AND PRACTICE OF CHEESE-MAKING

low, the coating will be too thick and will crack or
break away from the cheese more easily. About
5 or 6 ounces of paraffin will cover an 8o-pound
cheese, and the cost is about 2^ to 3 cents. Most
retail merchants are now in favor of having cheese
coated with paraffin ; but in England many of the
large exporters are not in sympathy with the idea,
although the number of the latter is gradually de-
creasing. If cheese is exposed to high tempera-
tures after the paraffin is applied, its beneficial effect
will be lost. For this reason, the average factory
cannot paraffin cheese, and it is usually done at
central cold-storage places, to which the cheese is
shipped.

WEIGHING CHEESE FOR SHIPMENT

Before cheese is shipped, each one should be
carefully weighed and the weights copied in dupli-
cate. Special cheese-shipping books are available
for this purpose. One copy is forwarded to the
purchaser of the cheese and the other is kept at
the cheese-factory. In most states, the cheese is sold
according to the exact weight of each, "balanced
beam." In Canada the factorymen are forced to
allow the buyers *'up-beam," plus ]A, pound. This
means that, for every cheese sold, the factoryman
gives away at least % pound. In many cases it is
more, because it is difficult for the cheese-maker to
have the cheese always weigh so near the pound mark.
Unfortunately, this has become an almost uncriticised
practice and it is hoped that cheese-makers in
Canada will soon awaken to a better method of selling
cheese.

CARE^ SHIPMENT AND SALE OF CHEESE "J^

BOXING CHEESE FOR SHIPMENT

After cheese is weighed, each is placed in a box
for shipment. A thin scale-board should be placed
between the cheese and each end of the box to
prevent the cheese sticking to the box. The box
should fit the cheese closeh^ and should be strong
enough to stand shipment without breaking. If
the box is too high, it should be pared down with
a draw-knife. The lid of the box should just press
lightly on the top of the cheese. Some shipping
companies demand that the lids be securely fastened
on every box. If the lids fit snugly, they will
not come off easily in handling; but if nails are
used, they should not be so long as to penetrate the
cheese.

STENCILING THE BOXES

The weight of the cheese should be neatly
stenciled on the side of the box in large figures
and, if the cheese is for export, the name of the
factory should also be stenciled on the side. It is
bad practice to mark the weights with a lead
pencil. Such marks do not look well and are often
very indistinct, since all cheese-makers cannot
make neat, plain figures. A rubber stamp is, per-
haps, the quickest and neatest way. If a brass
stencil is used, a mixture of coal-oil and lamp-
black makes a very suitable blacking. Shoe-black-
ing should not be used, because it easily becomes
smeared and then makes the package appear un-
tidy.

SCIENCE AND PRACTICE OF CHEESE-MAKING

DRAWING CHEESE TO SHIPPING POINT

Most cheese-factories are located in country
places some distance from railway and steamboat
facilities. The cheese is usually drawn to ship-
ping- places by patrons of the factory. In many
instances the wagons used are not fit for carrying
cheese, and the boxes that were clean and neat
become dirty or broken by the time they reach the

FIG. 13 — A CHEESE-BOX, AS IT SHOULD APPEAR
WHEN READY FOR SHIPMENT

station. The cheese should be drawn in clean,
spring wagons and should be placed so that the boxes
do not roll around and break. Clean straw placed
on the bottom of the wagon-box improves the con-
ditions of transportation. A covering of oiled canvas
placed over the load of boxes will protect them from
dust, rain and the heat of the sun.

HOW TO SELL CHEESE

When cheese-factories were first operated, the
cheese was purchased by buyers, who visited the

CARE, SHIPMENT AND SALE OF CHEESE 79

factories and bought the cheese on its merits. Now
most cheese is sold on the dairy boards of trade.
Large dealers send representatives to each cheese
board with instructions to buy cheese at a certain
price. Usually there is enough competition be-
tween buyers to insure the full market prices.
Buyers are allowed by their employer one-six-
teenth to one-eighth cent per pound for buying
cheese, and very often, in the heat of competition,
they pay the cheese seller this commission in order
to secure the cheese. This is not objectionable,
if it does not continue too long. If the buyer re-
ceives no pay for his work, he frequently finds fault
with or rejects the cheese and asks for a reclaim of
a few dollars from the cheese-maker, when other-
wise the cheese would pass inspection. In sections
where cheese is inspected in the factories, the cheese-
board method is fairly satisfactory, but when the
cheese has to be sent to a distant center of inspec-
tion, there is continual complaining by either buyer
or seller.

METHOD OF PAYING FOR CHEESE

With few exceptions, cheese is now shipped to
the order of some bank. After the buyer has in-
spected and accepted the cheese, he gives the seller
a draft of his firm on the local bank for the value
of the cheese. The bank then draws on the firm
and the cheese belongs to the bank till the draft
is honored. This method is a real cash business
and protects the factoryman from losses caused by
fraudulent practices of dishonest cheese merchants.

CHAPTER VIII

Commercial Qualities of Cheddar Cheese
and Methods of Judging

In commercial transactions in cheese, certain
points or qualities have been adopted as a basis
or standard in judging the commercial value of this
product. 7"he terms used in expressing the different
qualities vary considerably in different market cen-
ters, and the same expression is used with different
meanings by different persons. Frequently indi-
viduals use terms that are strictly local or per-
sonal. It is desirable that there should be a
uniform usage and a common understanding in re-
spect to the terms used in judging cheese. The
attempt is made here to discuss the terms in com-
mon use and to define them as well as may be, in
the hope that it may serve as an aid in bringing
about a general agreement in respect to the use
and understanding of the expressions employed
in judging and scoring cheese. The definitions
here given can hardly be expected to be in full agree-
ment with the usage of everyone, since individuals
differ from one another so much in their use of these
terms.

SAMPLING AND TESTING CHEESE

In testing its commercial qualities, a sample of
the cheese to be examined is obtained by means

JUDGING COMMKRCIAL QUALITIES 8l

of a cheese-trier. This is inserted nearly its whole
length, if possible, into the cheese, turned around
once and then drawn out, bringing with it, as the
sample, a long, round cylinder, commonly called

"plug."

The plug should always be drawn from the top
and not from the side, in order to avoid injuring the
protective po-wer of the bandage. The plug drawn
is examined by smelling, feeling, appearance, etc.,
in reference to the various qualities mentioned
below.

TERMS USED IN DESCRIBING QUALITIES

OF CHEESE

The following qualities have been selected to serve
as a basis in the commercial testing and scoring of
cheese: (i) Flavor, (2) texture, (3) body, (4) color,
(5) salt, and (6) appearance.

Flavor. — By flavor is meant the quality that is
perceptible to the smell and taste. The sense of
smell is depended upon in testing flavor in cheese
much more -largely than is the sense of taste, because,
in examining a large number of samples of cheese
in succession, constant tasting soon dulls not only
the sense of taste but also that of smell. Flavor in
cheese is due to the formation of some unknown
compound or compounds during the ripening process

(P- 375)-

Testing flavor in cheese. — The flavor is best ob-
tained by direct smelling of the plug as soon as it is
drawn and, in addition, by crushing and warming
some of the cheese between the thumb and fingers
and then smelling.

.82 SCIENCE AND PRACTICE OF CPIEESE-MAKI.^G

Terms used m describing cheese flavor. — Froi?i
a great variety of names applied to various flavors
found in cheese, the fohovving terms are selected
for consideration: (i) Perfect, (2) high or quick,
(3) clean, (4) low or flat, (5) strong, (6) too
much acid, (7) too little acid, (8) sour, (9) sweet
or fruity, (10) rancid, (11) tallowy, (12) tainted,
(13) stable, (14) weedy, (15) bitter, (16) cowy,
(17) fishy, (18) hydrogen sulphid.

(i) Perfect flavor applies to cheese when it some-
what resembles that of first-class butter with an added
quality of its own that is characteristic but cannot be
</^ -7^ described further than to call it cheese-like. It is
sometimes described as ''nutty." This flavor should
be marked, but not strong. It should be free from
all other flavors, particularly the more or less ofifen-
sive products of undesirable fermentations. The taste
should be mild and somewhat lasting, but should not
be so sharp as to "bite" the tongue.

(2) High or quick flavor is a delicate flavor that
disappears quickly.

(3) Clean flavor is free from every trace of un-
pleasant aroma or taste.

(4) Low or Hat flavor applies to slight traces, or
absence, of flavor ; it is insipid.

(5) Strong flavor is a good flavor very pronounced
but free from everything offensive ; it is a good flavor
strongly developed.

(6) Too much acid applies to flavor that smells
somewhat sour, but does not taste sour.

(7) Too little acid applies to a mild flavor, lacking
in character.

JUDGING COMMERCIAL QUALITIES 83

(8) Sour flavor is characterized by a sour taste
when the cheese is fresh, owing to the presence of
too much whey.

(9) Szveet or fruity flavor is suggestive of artificial
pineapple odor and is somewhat "sickish" to taste.

(10) Rancid flavor is that of butyric acid, more
common in old cheese than in young. When very
strong, it affects a delicate throat with a slight sensa-
tion of choking or strangling.

(11) Tallowy flavor is like that of tallow.

(12) Tainted flavor includes a variety of odors,
mildly to strongly offensive.

(13) Stable flavor suggests the smell of cow ma-
nure.

(14) Weedy flavor applies to such abnormal
flavors as come from onions, leeks, cabbages, rag-
weed, etc.

(15) Bitter flavor is self-descriptive. It is often
due to certain fermentations that develop when a
cheese is undersalted.

(16) Cowy flavor is suggestive of the breath of a
cow and may develop in cheese from some form of a
fermentation.

(17) Fishy flavor is self-descriptive. It is caused

by certain ferments that are present in milk. ^' ^^^^^-^^^^'^^^

(18) Hydrogen sulphid is a gas which gives the
odor that is characteristic of the water of sulphur-
springs. It is found in cheese ripened at high tem-
perature. The odor is rarely, if ever, as strong as in
the water of a sulphur-spring. A cheese with this
flavor, or a fishy flavor, is technically known as a
"stinker." The presence of this gas can be detected
by holding a bright silver coin against the cheese-phig

84 SCIENCE AND PRACTICE OF CHEESE-MAKING

FIG. 14 — CHARACTERISTIC AP-
PEARANCE OF A CLOSE-TEX-
TURED CHEESE

"body" as a part of
the texture, but the

for a moment ; the sil-
ver tarnishes if any ap-
preciable amount of
hydrogen sulphid is
present.

Texture. — Texture,
as apphed to cheese,
refers chiefly to com-
pactness or appearance
of soHdity. It is quite
common, unfortunate-
ly, to regard the

fs^r^^lilBilunfflffi^^t^- nf^ |j'ra!!!g^B41^-|!f"ig;

two quaHties are
clearly distinct and
should not be con-
fused.

Testing texture in
cheese. — The texture
of cheese is tested
by an examination of
the plug with refer-
ence to the presence fig. 15 — characteristic appear
of holes. The plug
is broken in two and

ance of a loose or porous
texture

FIG. 16 — TYPICAL TEXTURE OF SWEET-
CURD cheese

the broken ends
examined for the
characte ristic
flinty appearance.

Terms describ-
ing t e X t u r e. —
T h e following
terms are among

JUDGING COMMERCIAL QUALITIES

those most commonly used in describing texture:
(i) Perfect, (2) close, (3) loose, (4) mechanical
holes, (5) gas or pin-holes, (6) Swiss-holes.

Q Sf

♦

FIG. 17 EFFECTS OF GASSY FERMENTATION IN CHEESE

(i) Perfect texture in cheese is shown when a
plug or a cut surface of the inside of the cheese
presents to the eye a solid, compact, continuous
appearance, free from breaks, holes and chunks.

'ise

^•-

«i-'

FIG. 18 — MECHANICAL HOLES IN CHEESE NOT PERFECTLY

CEMENTED

86 SCIENCE AND PRACTICE OF CHEESE-MAKING

When a plug is broken in two, it should show a flak}"-
appearance, termed a ."flinty" break, resembling the
surface of broken flint or steel.

(2) Close texture describes the appearance of a
cut surface of cheese when free from all kinds of holes.
Such cheese is often described as "close-boring."
(Fig. 14.)

(3) Loose or porous texture is indicated by lack
of solid compactness, being more ■ or less full of

holes, which vary from
a few (Figs. 15 and 16)
to enough to make a
spongy (Fig. 17) ap-
pearance. One variety
is known as fish-eye,
due to action of yeasts
(p. 126).

(4) Mechanical holes
in cheese are irregu-
lar, open spaces,
caused by the incom-
plete cementing of the
pieces of curd in the press. (Fig. 18.)

(5) Gas-holes or pin-holes are small holes, pro-
duced by gaseous products of fermentation.

(6) Szviss-holes are fairly large, round holes, such
as are present in Emnienthaler cheese. (Fig. 19.)

Body. — This term, used in connection with cheese,
refers to the consistency, firmness or substance of
cheese. It is largely influenced by the amount of fat
and moisture in cheese.

FIG. 19 — SWISS-HOLES

JUDGING COMMERCIAL QUALITIES 87

Testing body. — This quality is found by pressing
a piece of cheese between the thumb and fingers.

Terms describing body. — The following terms are
among those used in describing the body of cheese :
(i) Perfect, (2) solid or firm, (3) smooth, (4) silky,
(5) waxy, (6) pasty or salvy, (7) stiff, corky or
curdy, (8) weak-bodied, (9) mealy, (10) gritty, (11)
watery, (12) overdry.

(i) Perfect body in cheese is indicated when it
feels solid, firm and smooth in its consistency or
substance. It does not crumble imder pressure. A
plug drawn from a cheese of perfect body should
be smooth in appearance and not ''fuzzy."

(2) Solid, -firm or meaty body is indicated when
cheese offers a certain amount of resistance under
pressure, somewhat like that shown by a piece of fat
pork or cold butter. The term meaty is also used.

(3) Smooth-hoditd cheese, when pressed between
the thumb and fingers, feels smooth and velvet-like,
as distinct from harsh, gritty or mealy.

(4) Silky-ho^\^d cheese is smooth in feeling but
not oversolid in consistency.

(5) Waxy-ho6\^d cheese is much the same as
silky, but possessing more firmness or solidity.

(6) Pasty or salvy cheese is very soft, usually
from an excess of moisture. When pressed, it sticks
to the fingers.

(7) Stiif, corky or curdy cheese is hard, tough,
overfirm ; it does not crush down readily when pressed

in the hand.

(8) Weak-hodit^ cheese is very soft, lacking in
firmness, but not necessarily sticky like pasty
cheese.

38 SCIENCE AND PRACTICE OF CHEESE-MAKING

(9) Mealy or crumbly cheese breaks down in fine
crumbs when pressed.

(10) Gritty-hoditd cheese feels harsh and gritty
under pressure.

(11) PVatery-hodied cheese is excessively soft,
pasty and sticky.

(12) In an over dry cheese the body is very hard
or mealy.

Color. — The color of cheese varies considerably,
whether artificially colored or not. There appears
to be an increasing" demand for uncolored cheese.
The coloring varies from a pale yellow to a red-
dish yellow, according to the demands of special
markets.

Testing color. — The color is tested by inspection
with the eye, the examiner noticing particularly
unevenness and any extreme condition of color.

Terms describing color. — Color in cheese is de-
scribed in the following terms: (i) Perfect, (2)
straight, (3) translucent, (4) white specks, (5)
streaked, (6) wavy, (7) mottled, (8) acid-cut, (9)
high, (10) light, (11) uncolored.

(i) Perfect color in cheese is indicated by even-
ness of color throughout the mass. A plug held
between the eye and light should appear somewhat
translucento

(2) Straight color is an even, uniform color
through the whole cheese.

(3) Translucent applies to color in cheese which
appears slightly translucent when the plug is held
between the eye and the light.

(4) White specks is a term that describes itself.
Such specks in cheese are a defect. They may

JUDGING COMMERCIAL QUALITIES 89

appear in cheese cured at low temperature (p.

(5) Streaked color indicates that there are light-
colored portions in the form of streaks.

(6) Wavy color applies to lighter portions appear-
ing in the form of waves.

(7) Mottled color shows in cheese in lighter-
colored spots of fairly large size, more or less
irregular.

(8) Seamy color applies to the appearance of a
pale rim surrounding each piece of curd and showing
the outline of the pieces as they were before being
pressed (p. 131).

(9) Acid-cut color is shown in cheese when con-
siderable portions of the cheese have been made
lighter in color by the presence of too much acid
(whey).

(10) High color is indicated by a reddish color,
caused by using too much coloring-matter. How-
ever, the question of color is a relative one, because
the demand in different markets varies from uncolored
to extremely high color.

(11) Light color is the term usually used in de-
scribing cheese that has been made uniformly dead
white by the action af too much acid (whey).

(12) Red spots are places, usually small in area,
having somewhat the appearance of iron-rust (p.

131)-

(13) Uncolored cheddar cheese Is not white, but of

a light amber shade.

Salt. — The amount of salt in cheese varies some-
what with different markets. There is seldom
experienced difficulty of uneven salting in cheese,

90 SCIENCE AND PRACTICE OF CHEESE-MAKING

because the salt slowly permeates the cheese in the
ripening- process. Little variations usually occur in
different parts of the same cheese, but are so slight
as to be incapable of being noticed by ordinary
methods of examination.

Testing cheese for salt. — The quality of cheese
as influenced by the salt is found simply by
tasting.

Terms used in describing salt. — In describing
the relation of salt to cheese, the following terms
are used: (i) Perfect, (2) too much, (3) too
little.

(i) Perfect applies to salt in cheese when just
enough has been used to impart a sufficient taste
of salt.

(2) Too much salt is indicated by salty taste. Too
much salt in cheese causes a dry, mealy, overfirm body
and imperfect flavor.

(3) Too little salt is shown by insipidity of taste.
It is usually accompanied by bitter flavor and porous
texture.

Appearance. — This term refers to the general
appearance of the cheese to the eye in respect to
uniformity, neatness and cleanliness. It may also
include the boxing. One system, as in the case of
butter, describes under "finish" the appearance of the
cheese, and under ''packages" the boxing; and we
will follow this method here.

Testing appearance. — When the cover of the box
is removed for sampling, in the case of boxed
cheese, the appearance of the cheese is noticed and
the box itself is examined. Cleanliness and neat-

JUDGING COMMERCIAL QUALITIES 9I

nesa are the points to observe in judging appear-
ance.

Terms describing appearance. — The general terms
used in describing appearance are (i) finish and (2)
package.

(i) Finish in appearance, in order to be perfect,
mur^t meet the following requirements : The rind
mur.t be smooth, even in color, free from cracks
and fairly hard. The bandage must be without
wrinkles and must be neatly rounded over the edges
about an inch on each end of the cheese. The sides
of the cheese should be straight and of uniform
height all around.

The faults of appearance in finish are as fol-
lows, the terms being self-descriptive : ( i ) Cracks,
(2) light spots, (3) roughness in rind, (4) uneven
edges, (5) wrinkles in bandage, (6) lack of uni-
formity in ends and in height, (7) bulging out at
sides or ends.

(2) Package. — The packages or boxes are re-
garded as perfect when of good material, well made,
strong, clean, close-fitting, uniform in size and in
undamaeed condition.

"^fe"

JUDGING AND SCORING CHEESE

The qualities described in the preceding pages
are used for judging and fixing the commercial
value of cheese. Judging cheese consists in making
an examination of a cheese with reference to the
various points of quality, which have been de-
scribed in the foregoing pages, as a basis for scor-
ing cheese, which consists in assigning to each

92 SCIENCE AND PRACTICE OF CHEESE-MAKING

•

quality a definite value, corresponding to its char-
acter as found in the cheese examined. In judging
cheese one must have in mind (i) the perfection
of quality in each case as a basis for comparison,
and (2) the proper perspective of the different
qualities in relation to each other.

Scale of points.— To each quality is assigned a
definite numerical value and these numbers are called
a scale of points. The different values assigned to
the various qualities indicate perfection in each
case and the totals aggregate 100. Slightly differ-
ent values are assigned in different cheese markets
and for cheese made by different variations in the
process of manufacture. Below we present ex-
amples of different types of scale of points:

Export cheese

Home-trade cheese

English market

Flavor

45
15
15
15
10

IS
10

Texture

Body

25 (quality)

Color

Appearance

(Finish)

10 (make)

In the case of home-trade cheese, a larger num-
ijer of points is allowed for perfect flavor, because
such cheese, on account of its high water-content,
easily develops poor flavor and, consequently,
flavor deserves more attention in judging and
scoring than in case of export cheese, which, with
smaller water-content, is more uniform in flavor.
Then, again, in home-trade cheese, closeness of
texture is not regarded as highly essential, the main
emphasis being given to body.

TUDGING COMMERCIAL QUALITIES 93

In explanation of the Eng-Hsh scale of points, it
may be stated that the majority of Englishmen pre-
fer cheese of considerable age, properly ripened and
rather sharp in taste, and it is this character which
they express by the word "quality."

Method of scoring. — In scoring a sample of
cheese, an examination is made with reference to
each of the qualities mentioned. In those qualities
in which it is perfect, it is given the values or
points assigned above. If the cheese is defective
in any quality, that is, short of perfect, then a
smaller value is given than the one indicated above
in the scale of points ; the more defective the cheese
is in any quality, the lower is the value or number
of points given it. When all the qualities have been
scored, the numbers of points assigned to them are
added and the total is the score of the cheese under
examination.

It can readily be seen that judgment, trained by
experience, is required to assign to each quality its
proper number of points. The sense of smell and of
taste must be highly developed by training in the field
of experience. The eye and touch must also be
trained by special experience in the actual work of
sampling, studying and judging cheese.

Score-cards. — For convenience, score-cards are
used in keeping records of the results of scoring
where many samples are examined. The following
form (see next page) illustrates a commercial score-
card.

In commercial scoring, reasons for the number
of points given are not stated ; but in dairy schools
and competitive public exhibitions, where educa-
tional purposes are in view, the reason for each

94 SCIENCE AND PRACTICE OF CHEESE-MAKING

Name or number identifying sample

Class or kind of cheese

Date Judge .

QUALITY

Score-points

Sample
1

Sample
2

Sample
3

Sample
4

Flavor

45
15
15
15
10

42
14
14
15
10

40
13
15
14
8

36
12
12
13
10

Texture

Body

Color

Appearance

score should be given. The educational feature
should be made especially prominent at country
and State agricultural fairs, at conventions of dairy-
men's associations, etc. There is, and has been,
altogether too little attention given to the educa-
tional feature ; the main, and usually the sole, pur-
pose has been to capture prizes. Such occasions
can be made extremely valuable in an educational
way by indicating in detail the defects and then
indicating how these may be overcome. The follow-
ing form of score-card for such purposes is a sugges-
tion, which may be modified to suit any special
conditions :

EDUCATIONAL CHEESE-SCORING CARD

Date Judge .

Class

Name or number identifying cheese . . . .

NUMERICAL SCORE

Qualities: Flavor Texture Body Color Appearand

Ifrill^^: ] « 15 " >S >0

Score given ; ,

Total score:

JUDGIXG COMMERCIAL QUALITIES

DESCRIPTIVE SCORE (Check defects in list below)

Flavor

Texture

Body

Color

Appearance

Perfect

Clean Quick

Finn

Straight

Finish:
Perfect

Flat Strong

Porous

Smooth

Translucent

Cracks,
Light spots

Too much acid

Mechanical -holes

Silky

Light

Rough rind

Too little acid

Pin-holes

Waxy

High

Uneven ends

Sour Bitter

Swiss-holes

Pasty

Mottled

Uneven edge

Cowy Stable

Fish-eye-holes

Weak-bodied

Streaked

Wrinkles

Sweet or fruity

Stiff or corky

Wavy

Bulging

Weedy Rancid

Crumbly

White specks

Packages:

Tallowy Fishy

Gritty

Seamy

Perfect

Tainted

Watery

Acid-cut

Clean Dirty

Hydrogen-sulphid

Overdry

Red spots
Uncolored

Neat Unif'm
Loose Close

Remarks

Advice for overcoming defects .

Methods of grading cheese. — The classification
of cheese according to the resuUs of judging and
scoring varies in different markets, the method in
each case being arbitrary. For ilhistration, one
classification is into (i) ''fancy," (2) ''firsts" and (3)
"seconds." In the Canadian market, there are first,
second and third grades.

CHEESE-MAKERS AND JUDGING CHEESE

It is a matter of regret that cheese-makers do
not have more extended practical experience in
iudsrine cheese. Everv cheese-maker who desires
to acquire greater efficiency in his work should
own a good cheese-trier and use it as often as
practicable. It is well before shipment to examine
one cheese from each day's make and then study

g6 SCIENCE AND PRACTICE OF CHEESE-MAKING

the results in connection with the record of corre-
sponding date, giving the details of the conditions
of manufacture. This is frequently impracticable,
because cheese is shipped before it can be properly
judged. Then, again, cheese which appears well when
shipped may develop imperfect qualities later ; while
some cheese, imperfect at the start, may improve later
if kept under proper conditions.

CHAPTER IX

Cheese-Factory Construction

A cheese-factory should be a model of cleanliness
in every dairy community. At the present time the
word cheese-factory does not stand for any such ideal
condition. In the construction or remodeling of fac-
tory buildings, attention should be given to the follow-
ing points: (i) Location and site, (2) material to
be used, (3) architecture, (4) water-supply, (5)
drainage, and (6) curing-rooms.

LOCATION AND SITE

The selection of a suitable location and site Is one
of the most important factors in cheese-factory con-
struction. The factory should be centrally located
and, if possible, on a hillside where advantage may be
taken of gravity and other natural conditions.

Before we were familiar with the importance of
sanitation, cheese-factories were invariably erected on
low, wet ground where a water-supply could easily
be obtained. No attention was paid to the means of
disposing of the excess of whey and of sewage from
the building. The result was that in a short time the
soil surrounding the factory became saturated with
decayed waste products ; the water-supply was made
impure from the same source; in hot weather, flies
gathered in large numbers, carrying bacteria and dirt

98 SCIENCE AND PRACTICE OF CHEESE-MAKING

from the stagnant surroundings into the vats con-
taining milk and curd. As a result of these condi-
tions, bad flavors appeared in the cheese, and cheese-
makers experienced all sorts of difficulties in the
factory operations. Most of these bad conditions
have since been removed or remedied, but in many-
parts of the country they are still to be found. In
Ontario, Canada, especially, great improvement has
been made in the sanitation of cheese-factories since
the passing of a special law and the appointing of
special sanitary inspectors. Most factorymen now
appreciate the value of cleanly conditions surrounding
the entire manufacturing process, but many must be
forced to put their buildings and equipment in proper
condition.

MATERIAL TO BE USED

Appearance, cheapness, durability and efficiency
should be kept in mind. Brick buildings are to be
preferred, and, while their first cost is greater than
wood, they are the most durable and cheapest in the
end. Cement, when properly made and used, makes
an efficient, fairly cheap and durable building. Stone
and wood are commonly used. The relative economy
with which the building material can be obtained will
largely influence the character of buildings erected in
diflferent localities.

ARCHITECTURE

Plans and blue-prints of modern cheese-factories
are always available, free of charge, from the agricul-
tural departments of the different governments, so

CHEESE-FACTORY CONSTRUCTION 99

that it is unnecessary in this treatment of the subject
to go into details. Suffice it to say that the architec-
ture should be simple, attractive and convenient. The
location and site will determine to a great extent the
style of architecture.

WATER-SUPPLY

Nothing is of more importance in factory construc-
tion than the water-supply. The quality should be
pure and an abundance of it should be assured. The
purity of springs, deep wells, rivers, and lakes with
a large outlet can usually be depended upon, but the
character of the surrounding area drained must be
considered. Surface water, by all means, should
be kept out of the wells. If milk or whey enters a
well accidentally or otherwise, the water soon becomes
contaminated and unfit for use. When this occurs,
the water should be pumped out and the well thor-
oughly cleaned.

DRAINAGE

Drainage is so closely related to the water-supply
that they are naturally considered together. If pos-
sible in any way, natural drainage should be secured.
In cheese-factory work there is usually a considerable
volume of sewage, consisting of wash water and
excess of whey. The best method for its disposal
is now attracting the attention of factorymen and
of those who enforce the laws of health and sanita-
tion. The character of sewage at all cheese-factories
is practically the same. The method of its disposal

lOO SCIENCE AND PRACTICE OF CHEESE-MAKING

will depend on the water content, the character of the
constituents, and slope of the surrounding soil The
waste or superfluous whey is the main cause for need
of improved sanitation at cheese-factories. If it
were not for this, the wash water could be more
easily disposed of. However, the following methods
have given excellent satisfaction when properly in-
stalled under suitable conditions.

Removal by cartage. — This system requires a
storage-tank for wash water as well as for whey,
although many factorymen allow the wash water to
run into the whey-tank. Arrangements are made by
which some person agrees to remove all sewage from
the factory to some river, lake or satisfactory place
of disposal and to clean the whey-vats at stated times
in return for the superfluous whey he may receive
to use for feeding purposes. As a rule, this method
is satisfactory, and its use is advised when the others
are not more practicable.

Direct disposal into large lakes and running
streams of water. — Many factories are located on
the banks of lakes and rivers, into which it is usually
an easy matter to conduct the sewage by means of
piping or tile. This makes an ideal method, if the
body of water is large or has sufficient current to
carry it to a suitable outlet.

Septic-tank system. — This consists of a series of
tanks, in which the sewage is treated before being
allowed to flow out into or on top of the surrounding
ground. The number and size of tanks will depend
on the size of the factory and the character of soil
into which the treated sewage must pass. Fig. 20
fllustrates a plan for a factory with n daily capacity

CHEESE-FACTORY CONSTRUCTION

lOl

for 10,000 pounds of milk, whose treated sewage
passes out into heavy soil with little natural drainage.
The material used in tank construction can be iron,
cement or wood. Each part should be large enough
to hold the sewage of 24 hours. By this arrangement
the sewage is in the tank for three days. At the
end of this period it may be carried by piping or tile
to its final place of deposit. The overflow-pipes
should be ventilated to prevent siphoning of the con-
tents after it starts to overflow. The tanks are

JinW/TTER PIPC

FROM TACTORV

SEWAGE
OF
FIRST DAY

t-
z

SC'.'

c«/

a.
a
z
o

a.
C

z
o

P
z
u

.4' SOIL TILE

SFWAGE

THIRD

DAY

0ISP03A

FIG. 20 SERIES OF SEPTIC TANKS CAPABLE OF HOLDING

THREE days' SEWAGE FROM A CHEESE-FACTORY
HANDLING 10,000 POUNDS OF MILK A DAY

better placed under ground so that the top just
reaches the surface. It should have a good top and
may then be covered with earth. It is advisable to
have a water-trap in the pipe delivering the sewage
from the factory lo the septic tank in order to pre-
vent odors returning. This system is very efficient
and may be used in almost any locality. In some
places it is advisable to deposit the treated sewage
on a prepared, gravel filter-bed.

I02 SCIENCE AND PRACTICE OF CHEESE-MAKING

Cesspools. — When the surrounding soil is of sand
or gravel, the cesspool makes an efficient and cheap
method for sewage disposal. For a factory with a
daily capacity of 10,000 pounds of milk, a cesspool of
the following dimensions and construction is ad-
vised: A hole 12 feet in diameter and 6 feet deep
is excavated. This should be lined with loose stones
up to within one foot of the ground surface. Over
this, cedar logs, with good supports, are placed at
intervals of 24 inches. A plank covering goes over the
logs, and this again is covered with earth, making the

DOOR

FOR

PILLINIi

SLIDE TRAP DOOR -h^ WARM AIR

SOLID ICE.

^—-\

CURING ROOM

SLIDt TRAP DOOR ± . .., _ ^.„

DRAIN-i^ >COLD AiR

"///7//////MM. ,..„PB£ilN-jr

z
S

\-
u

Z
<

S- SHAPED l"PIPE FROM
DRA(N IN ICE-HOUSE

FIG. 21 — PLAN SHOWING SATISFACTORY METHOD FOR SECUR-
ING CIRCULATION OF COLD AIR IN CHEESE-CURING ROOMS

Spot unnoticeable. A cesspool should be located at
least 20 feet away from the buildings, and on the lower
side of the source of water-supply. The pipe lead-
ing from the factory floor to cesspool should have
a water-trap to prevent returning odors. It is advis-
able to place on all whey-tanks an overflow pipe con-
nected with the drainage deposit.

CURING-ROOMS

A curing-room should be so constructed that the
temperature and humidity can be controlled. It should

CHEESE-FACTORY CONSTRUCTION

103

have good ventilation, insulation and circulation of
pure air. Under ordinary conditions, ice provides
the cheapest and most efficient method of maintaining-
a uniformly cool temperature in curing-rooms. In
large cheese-making centers, artificial refrigerating
machines are used, but they are too costly for ordinary
cheese-factories. Sub-earth ducts have proved unsatis-
factory, since they are too often least efficient when
most needed.

ORAINAGE OrSPOSAl/^ JSEPTIC TANKS OR CESS-POOL

WHEY TANKS

ICE HOUSE

I CURING SHELVES

STORE-
ROOM

COAL A
WOOD

BOILER ROOM

PRESS

VAT

PRE-SS

'STARTER
I ROOM

IsInK A

WASH
IRODM

WEIGH

CAN
OFFICE

FIG. 22 — MODERN PLAN SHOWING IDEAL ARRANGEMENT OF
CHEESE-FACTORY ROOMS AND EQUIPMENT

The drawing on page 102 (Fig. 21) provides a
scheme by which the air in the curing-room has a
continuous circulation over a bed of solid ice

The curing-room and ice-house should have good
insulation secured by the use of lumber, building-
paper, air-spaces, shavings and cement floors. The
ice-house should be one-third the size of the curing-
room. Three thicknesses of lumber, one of damp-
proof paper, and 6 inches of shavings provide

J 04 SCIENCE AND PRACTICE OF CHEESE-MAKING

sufBcient insulation for the curing-room. For the ice-
house an extra thickness of hunber and damp-proof
paper is advised in both ceihng and wall construction.
The ice-house floor and walls halfway up are lined
with galvanized iron.

The construction of the floor in the ice-house is
important, as provision must be made for protecting
the ice from the warm temperatures of the soil under-
neath. A cement floor with gravel and stone support
is first constructed. Over this, 2-inch by 4-inch sup-
ports are placed on edge at intervals of 18 inches.
Between these the space is filled with coal cinders
or shavings. Over this a 2-inch plank floor is laid,
and this covered with galvanized iron. A drain 2
inches by 2 inches should -be made in the ice-house
floor close to the curing-room wall, toward which
the ice-house floor should incline. The drain is neces-
sary to carry off the water from the melting ice. A
close-fitting S-shaped pipe with water-trap should
connect the drain with outside disposal. Over the
galvanized floor is placed a rack made of 2-inch by
4-inch supports on edge. This prevents the ice from
lying in water when it starts to melt. During the
winter months, the ice-house is packed full of ice.
No sawdust is used, the insulation being sufficient to
protect it

As Figure 21 shows, small trap-slides are placed
near the ceiling and floor between ice-house and cur-
ing-room. As soon as these are opened, the warm air
in the curing-room enters the openings at the top,
passes over the ice and out through the lower openings,
thus creating a circulation of cold air through the
curing-room, A uniform temperature of from 52®

CHEESE-FACTORY CONSTRUCTION

105

to 56° F. can be secured throughout the entire sum-
mer season in this way, and a uniform percentage of
moisture is also assured

When this system is not used, the curing-room air
may be cooled by hanging up large pans filled with
ice, but the moisture from them generally stimulates
mold formation. Where cold running water is avail-
able, it can be conducted through a system of coil-
pipes around the walls of the curing-room and the
temperature considerably lowered.

BOXING AND SHIPPING SPACE

12X26-

FIG. 23 — PLAN FOR CHEESE-FACTORY HANDLING 12,000 TO
20,000 POUNDS OF MILK A DAY. (BaCf)

A— Boiler; B— Engine ; C— Sterilizine-oven ; D— Weigh-can and scales ; E— Con-
ductor-spout; F— Bottle-rack ; G— Milk-tester ; H— Wash-sink; I— Cheese-vats;
j_Curd-sink; K— Steam-radiators ; L— Cheese-presses; M— Truck; N— Curing-
shelves.

CHEESE-FACTORY PLANS

As a suggestion, we give the outline of a plan for
cheese-factory construction with special reference to
convenience of arrangement for equipment. (Fig.
22.)

We give also an outline plan published by Ij. So
Baer, of Wisconsin. (Fig. 23.)

CHAPTER X

Cheese-Factory Equipment

A cheese-factory should be so equipped that every-
thing may be easily kept clean. The vats, presses,
sinks and all utensils should be placed in positions
that will insure convenience and a minimum amount
of labor. Too many factories at the present time
are not large enough for the equipment they contain,
and they consequently appear untidy and dirty to
visitors or to persons inspecting the conditions sur-
rounding the manufacturing process. Very often, too,
the utensils are not clean for the reason that the
cheese-maker, being short of help, neglects part of
the work. Utensils and equipm'ent, properly ar-
ranged, will save a great many steps to the cheese-
maker in a day. (Figs. 22 and 23.)

Advice, which is the result of varied experience and
which is often of considerable help to persons in need
of such assistance, can always be secured from ex-
perts employed by the different departments of agri-
culture.

The following apparatus is sufficient for a factory
handling 10,000 pounds of milk daily.

(i) One i2-horse-power, return-flue, horizontal
boiler with fixtures.

(2) Two steam-heating cheese-vats, with a capac-
ity of 7,000 pounds each. In recent years, wood suit-
able for making cheese-vats has become expensive and
hard to secure. Many manufacturers are using wood

106

CHEESE-FACTORY EQUIPMENT

107

of a poorer quality, and the vats are not durable.
Steel vats have been placed on the market and are
-living general satisfaction. They are preferable to
tne average wooden vat now manufactured. (Fig.
24.)

(3) Whey-tank, capacity of 12,000 pounds. If the
factory is so located that its elevation permits the load-
ing of whey without pumping, then one large tank can
be used. However, two smaller tanks connected by
an overflow-pipe are* preferable, because, when one is
empty, it can be cleaned while the other contains whey.
Steel tanks are preferable to wooden or cement ones.
They neither leak nor absorb, are easily cleaned, and
are more durable. Cement tanks are not durable.

FIG. 24 — ONE TYPE OF STEEL CHEESE-VAT

because the acid and salt in the whey destroy the
cement.

(4) One 600-pound, double-beam scale. Scales
are in daily use at cheese-factories and it is advisable
to purchase only those that are reliable and guaran-
teed, such as the ''Fairbanks" and "Howe."

(5) One 70-gallon weighing-can with a 3-inch
gate.

(6) One milk-conductor and head.

(7) Apparatus and alkali for testing acidity.

108 SCIENCE AND PRACTICE OF CHEESE-MAKING

(8)
(9)

(10)

knife.

(12)

(13)
(H)

(IS)
able.

(i6)

One Marschall or Monrad rennet-test.
One 3-8-inch, horizontal, steel curd-knife.
One 5-16-inch perpendicular, wire euro-
Two small solid-handle dippers.

FIG. 25 — BARNARD^S CURD-CUTTER

One strainer-dipper.

Two curd-agitators of McPherson type.

Two curd-rakes.

Two thermometers, strictly correct and reli-

One outfit for making commercial starters.

FIG. 26 — GOSSELIN CURD-MILL

(17) Two whey-strainers for each vat.

(18) One large knife for cutting curd.

(19) One curd-mill. A curd-mill should be so
constructed that its knives will go against the curd

CHEESE-FACTORY EQUIPMENT

109

in cutting-. The curd should not be pushed against
the knives. Such mills as the Barnard (Fig. 25),
Beech and Gosselin (Fig. 26) are recommended.
They can be had in hand or steam-power.

(20) Two -curd-stirring forks of wood or steel,
with points turned over so as not to puncture the tin
vats during stirring,

(21) One curd-scoop.

122) One fiat-sided curd-pail.

(2;^) Two steel-frame, automatic, continuous-pres-
sure gang-presses with hoops, followers, etc., com-

FIG. 27 — CONTINUOUS-PRESSURE GANG-PRESS

plete. (Figs. 2y and 28.) Galvanized-steel followers
are preferable to wooden ones, as they are more sani-
tary, are not absorbent, do not expand or contract
readily, and are more durable. Galvanized rings
are preferable to the fiber or rubber ones for the same
reasons.

(24) One 240-pound cheese-scale.

(25) One 24-bottle Babcock milk-tester.

(26) Two composite-sample bottles for each
patron.

no SCIENCE AND PRACTICE OF CHEESE-MAKING

{2.y) If the whey is to be separated and whey-
butter made from the fat, a separator and machinery
for butter-making- will be necessary.

(28) An instrument for deteriiiining- the amount
of moisture in the air of the curing-room. (Fig.

29-)

(29) A sterilizing-oven for sterilizing milk to be

used in the preparation of starters and also for the
sterilization of the smaller utensils employed in the
cheese-factory will be found convenient and highly
useful. Home-made sterilizers can be used with good

FIG. 28

FRASER HOOP

WILSON HOOP

A — Complete hoop; B— Bandasfes;
C — Follower; D— Fibrous press-ring.

A— Complete hoop ; B— Bottom cov-
er with wide flange ; C— Top cover with
narrow flange ; D— Closed or tight lioop
or body; E— Open hoop or bar.dages.

results. A galvanized-iron box, double-jacketed, is
arranged to admit steam between the walls. An open-
ing in the top of the outside wall is arranged to regu-
late steam pressure and another at the bottom to carry
ofif condensed water. The outside may be protecte'd
by a covering of asbestos or other boards.
(30) One Ouevenne lactometer.

FACTORY FURNISHINGS

Fuel, coal or wood.

Rennet-extract (Hansen's is recommended).

CHEESE-FACTORY EQUIPMENT

III

Cheese color (Hansen's is recommended),

Commercial starter.

Vat-brooms.

Floor-brush.

Washing-powder.

Cotton for press-cloths.

HYGRO-AUTOMETER

FIG. 29 — APPARATUS FOR INDICATING

PERCENTAGE OF MOISTURE IN AIR

OF CURING-ROOM

Cheese-bandage. This should be seamless and the
size %. inch smaller than the diameter of hoops ; a
cheese retains its shape better with such bandage.

Cheese-circles.

Cheese-salt. Paper-lined barrels are preferable.
The salt should be regular cheese-salt. Fine butter-
salt dissolves too rapidly and does not penetrate the

112 SCIENCE AND PRACTICE OF CHEESE-MAKING

curd SO well. Such brands as Windsor, Diamond,
Crystal, Genesee, LeRoy, Warsaw and Worcester are
generally reliable.

Cheese-boxes. These are made of both wood and
paper. If properly made, either material is satisfac-
tory. The boxes should be strong enough to stand
handling in shipping, and they should fit the cheese.
One-quarter inch between the cheese and box is suf-
ficient.

Scale-boards.

Milk-sheets.

Blanks for records of conditions of cheese-making
(p. i6).

Blanks for reports to patrons.

Milk-record books.

Cheese-shipping books.

Materials and stencils for branding boxes.

It is a great mistake for factorymen to purchase
cheap furnishings just because they are cheap. Cheese
of the best quality is the most profitable to make, and
no cheese-maker can afford to use poor furnishings if
he expects to have his cheese of finest quality and
appearance.

Part II

Defects of American Chedda

Cheese in Flavor, Body, Tex^

ture, Color and Finish:

Causes

Remedies

Means of Prevention

CHAPTER XI

Defects in Flavor

In this and several chapters following, an effort
is made for the first time to present in systematic
form a discussion of the imperfections that are most
commonly found in our American cheddar cheese.
The need of this requires no explanation, and the
importance of the subject is only too obvious. The
extent of defects in our cheese is well known and
also their demoralizing effect upon the industry. In
reality, the whole aim of the cheese-maker is, of
course, to produce cheese free from imperfections.
In discussing the subject, it is necessary to know (i)
what the defects are, and (2) to what causes they
are due. We are then in position to consider remedies
and means of prevention. The subject will be pre-
sented under the following divisions:

Defects in

( 1 ) Flavor.

(2) Body.

(3) Texture

(4) Color.

(5) Finish.

In each division, the presentation will give (l)
description of defect, (2) causes, (3) methods of pre-
vention and (4) remedies. It is important to know
how to prevent the recurrence of conditions that are
responsible for cheese-making troubles, and also how

Il6 SCIENCE AND PRACTICE OF CHEESE-MAKING

to handle the details of the cheese-making proces!:
when the presence of the trouble is recognized. The
facts will be presented more or less in outline form,
in order to make reference to them more convenient.

ACID FLAVORS

These are indicated by a sour smell and taste.
Cause :

(1) Over-development of acidity during the process ot

cheese -making, which is commonly due to —

(a) Ripening the milk too much before adding
the rennet.

(b) The use of too much starter.

(2) Any condition that retains in the curd and cheese an
excessive amount of whey (p. 46).

Prevention :

(1) Have less acidity in the milk before adding rennet-

extract. Sour milk, or milk over 0.26 per cent in
acidity, should not be accepted from any patron.
High acidity can be overcome by patron, if he will
cool milk to 60° F., or better 50° F., at once after
milking.

(2) Use less starter. Generally ^ to 2 per cent is sufficient.

(3) Add the rennet when such a degree of acidity is

present that the curd will become firm in the whey
before developing the desired amount of acid.

Remedy :

(See the treatment given under remedy for acid body (p. 122).

OFF FLAVORS

These are flavors that are not clean, such as rancid
or butyric acid flavor, stable or cow-manure flavor,
fishy flavor and hydrogen sulphid or sulphur-spring
flavor. When these develop so as to become very
strong, they are called "stinkers."

DEFECTS IN FLAVOR II7

Cause :

Undesirable bacteria, which gain entrance to the milk or
to the curd, commonly due to —

(1) Failure of patrons thoroughly to wash and scald all

cans and utensils coming m contact v.-ith the milk.
This is particularly true of cans in wmch whey is
carried from the factory,

(2) Careless milking in unclean places.

(3) Allowing the milk to become exposed, after milking.

in places where the air is impure.

(4) Keeping the milk at too high temperature.

(5) Using an unclean strainer at either the farm or cheese-

factory.

(6) Using utensils in the factory that have not been

thoroughly cleaned and scalded.

(7) Using badly-flavored starters.

(8) Using impure water for diluting rennet.

(9) Soaking curd in impure water after nulling.

(10) Using tainted rennet or salt.

(11) Ripening cheese at temperatures above 65° F.
Prevention :

Strict cleanliness in the production and handling of
milk and throughout the whob cheese-making process
(pp. 8, 17).

(1) All utensils, especially the milk-strainer, should be

thoroughly washed with warm water, using washing-
powder, and then scalded with live steam,

(2) Milking should be done m clean places, where dust.

cobwebs and flies are not present.

(3) Milk should be cooled to at least 60°, and better 50°

F., immediately after being drawn from the cow.

(4) Tainted milk should not be received at the factory

from any patron. If uncertain of the source of
tainted milk or curd, use the fermentation test on
each patron's milk (p. 434).

(5) A small amount of clean-flavored starter should be

used.

(6) Impure or bad-smelling water should not. be used.

(7) There should be screens on the doors and windows to

prevent the entrance of flies.

(8) When curd is washed, only pure water should be

used.
Remedy :

(1) Firm the curd a little more than usual in the whey by
raising the temperature.

Il8 SCIENCE AND PRACTICE OF CHEESE-MAKING

(2) Develop a little more acidity before removing all the

whey

(3) Mill the cuid early and expose well to fresh air by

stirring for some time immediately after. Excellent
results can be secured at this time because each
small piece of curd has six freshly cut surfaces which
permit the gases and odors to escape.

(4) Increase the amount of salt in curd in extremely bad

cases.

(5) Ripen the cheese at low temperature.

FRUITY FLAVORS

These are sv/eet flavors, having an odor like that of
certain ripe fruits, such as pineapple, raspberry and
strawberry. Such flavors are not pleasant to the taste
and are rather sickish.
Cause :

(1) Bacteria or yeasts carried into the milk by dirt.

(2) Transporting both milk and whey in the same cans

when not properly cleansed.

(3) Exposing milk near hog-pens where whey is fed.
Prevention :

(1) Cans used for delivering milk should not carry whey,

unless they are emptied and thoroughly cleansed
immediately after being brought from the factory.

(2) All whey should be pasteurized at the factories. This

would not only reduce greatly the source of badly
flavored milk, but it would eliminate the danger of
transmission of tuberculosis through the whey.

(3) The whey-tanks should be cleaned and scalded at

least twice a week. A steel tank has the following
advantages: It is more durable than wood or ce-
ment, does not leak, does not absorb whey, is easily
cleaned, and is cheaper in the end.

(4) Use a clean- flavored commercial starter.
Remedy :

(1) Firm the curd a little more in the whey by raising the

temperature.

(2) Develop a little more acidity before removing whey.

(3) Air the curd well after milling.

(4) In extreme cases use more salt in the curd.

DEFECTS IN FLAVOR IIQ

BITTER FLAVORS

Indicated by a bitter taste and a weedy odor.
Cause :

(1) Bacteria and yeasts.

(2) Allowing cows to wade m and drink from stagnant

pools.

(3) Using rusted milk-cans or other utensils.

(4) Using old starters that have developed too much acid.

(5) Using milk delivered in cans m which sour whey 'a cm

dirty tanks is carried.

(6) Too little salt in curd.
Prevention :

(1) Milk should be cooled to at least 60° F., and better to

50° F., immediately after milking.

(2) Rusted cans or utensils of any kind should not carry

milk.

(3) Cows should have only good water.

(4) Clean-flavored starters only should be used.

(5) Avoid the use of too little salt m the curd.

Remedy :

(1) Very little acidity should be developed before remov-

1' ing the whey.

, (2) Firm the curd more than usual. Heat it higher in the

' whey and stir it drier when removing the whey.

(3) Mill early and expose well to fresh air by stirring.

(4) In extreme cases use more salt m the curd.

FOOD FLAVORS

These include flavors characteristic of the foods

eaten by cows. A food flavor can be distinguished

from one produced by bacteria in that a bacterial

flavor usually gets worse as the cheese ages, while a

food flavor generally passes off to some extent (p. 8).

Cause :

(1) Such foods as turnips, onions, leeks, weeds, garlic,
rape, decayed ensilage and certain green fodders
Cd. 7)

120 SCIENCE AND PRACTICE OF CHEESE-MAKING

(2) Exposing milk in an atmosphere where any of these

are exposed.

(3) Storing milk in cellars where decayed vegetables zre

present.

Prevention :

(1) Foods that impart any objectionable flavor to milk

should not be fed or made accessible to the cow.

(2) Use a good commercial starter.

(3) Careful and thorough aeration (p. 12) of milk is often

helpful in removmg odors derived from foods

Remedy :

(1) Heat the curd several degrees higher in the whe3^

The high temperature helps to drive off the volatile
flavors.

(2) Air the curd well, especially after milling.

(3) Ripen the cheese at a low temperature.

CHAPTER XII

Defects in Body and in Texture

Dry Body

Shown in cheese that is too firm, mealy, rubbery
or corky.

Cause :

Lack of moisture or milk-fat or both, produced by —

(1) Removing part of the fat from milk.

(2) Too high heating in the whey.

(3) Heating too long.

(4) Too much stirring at the time of removing the whey.

(5) Using too much salt.

(6) Curing cheese in an atmosphere that is too dry or too

hot.

(7) A "high-cooked" cheese is rubbery or corky; one that

has been stirred too dry is mealy or sandy; and one
that is dry from excess of salt tastes salty. This is
a convenient way of determining the cause of such
defects.

Prevention :

(1) All the milk-fat should be retained in the cheese as

far as possible.

(2) The lower the temperature used in properly firming

the curd, the better will be the texture of the cheese.

(3) Be absolutely sure of the correctness of the thermome-

ters used.

(4) Give attention to the moisture content of the curd;

stir the curd as conditions require; and use the
proper amount of salt.

Remedy :

(1) Pile '}' — curd higher.

(2) Keep tnt a^r moist by placing hot water in the vat.

(3) Do not mill the dry curd early.

(4) A dry curd can be made mellow by soaking in cold

water after milling, but the cheese will not have
good-keeping quality.

(5) Use less than the usual amount of salt.

121

122 SCIENCE AND PRACTICE OF CHEESE-MAKING

(6) Paraffin the cheese as soon as practicable.

(7) Ripen the cheese in a cool room where the humidity

of the atmosphere is at least 80 per cent.

ACID BODY

Cheese under this head may be either dry or moist,
but in either case is of a mealy or sandy character.
It has a sour taste.
Cause :

(1) Overripe milk.

(2) Ripening the milk too much before adding the rennet.

(3) The development of too much acidity during the

cheese-making process, especially before the whey
is removed.

(4) Acid or sour cheese is most frequently caused not by

developing too much acidity, but by^ having the
curd insufficiently firm in the whey when the acidity
has developed.

(5) Using large amounts of starter.

Prevention :

(1) No sour milk, or milk containing more than 0.26 per

cent of acidity, should be received from any patron.

(2) The rennet should be added when the milk is at such

a stage of ripeness that there will be time to firm
the curd in the whey before too much acidity has
developed.

(3) Do not use too much starter.

(4) Keep the development of acidity under control by

controlling the amount of whey in the curd.

Remedy :

The method of handling overripe or sour milk, when it is
absolutely necessary to make such milk into cheese, is as fol-
w\ lows :

(1) Heat the milk not above 84° F.

(2) Use an extra amount of rennet.

(3) Cut the curd into smaller pieces.

(4) Heat higher. The degree of heat will depend on the
rapidity with which the acidity is developing.
Most fast -working curd contracts rapidly and there-
fore the raising of ihe temperature can be hurried.

DEFECTS IN BODY AND TEXTURE 1 23

(5) As soon as possible after heating, the whey should be

tun down to the level of the curd. This greatly
facilitates stirring and firming the curd, and, if more
than one vat is being used, time is saved when the
remainder of the whey is to be removed. If by this
time the curd is not firm and shows too much acidity,
a sour cheese can be prevented by,

(6) Removing the whey and putting on water at a temper-

ature of 102° F. The amount of water used and the
time it is left on will depend on the amount of
acidity in the curd. In extreme cases, it may be
necessary to give a second treatment with water.
As soon as the curd becomes firmed in the water
and the acidity is reduced to a normal amount, the
water should be removed. The curd should then
be treated like a normal curd. This method is not to
be confounded with the "soaked-curd" process,
which is entirely different.

(7) If, after milling, the curd is sour, it can be improved

by washing in pure water at 80° F. This resembles
the "soaked-curd" process, and, as a rule, such
cheese does not keep well. However, it is much
better to do this than to allow the cheese to sour,
and the process should be used in extreme cases.

(8) Use an extra amount of salt after washing.

LOOSE OR OPEN TEXTURE

Cheese with this texture is full of holes. Such
cheese is generally soft in body. Such defects are
more serious when found in export cheese, since a
"close-boring" cheese is demanded for this trade.
Cause :

(1) Developing too little acid and retaining too much

whey.

(2) Putting curd to press at too high a temperature.

(3) Lack of pressing.

(4) Soaking curd in water after milling.

Prevention :

(1) Have at least 0.24 per cent of acidity m whey run-
ning from curd after it is piled for cheddaring.

(2^ The curd should be cooled to 80° F., at least, before -- /^
pressing. This can be hastened by runn;ng cold
Vvater around the outside of the vat lining

124 SCIENCE AND PRACTICE OF CHEESE-MAKING

(3) Pressing for 48 hours is much better than for 24.

A continuous pressure is of more value than a heavy
pressure for a short time.

(4) Curd should not be soaked in water.

Remedy :

(1) Open-textured cheese can be closed up to some extent

by pressing again.

(2) Ripen at lower temperatures.

GASSY CHEESE TEXTURE

Indicated by the presence of pin-holes. Such
cheese usually has a bad flavor, is spongy, and the curd
may float on the whey in the early stage of cheese-
making.

Cause :

(1) Milk infected by gas-producing bacteria, which are

carried in by dirt.

(2) Starters infected by gas-producing bacteria.

Prevention :

(1) Gassy milk should not be accepted from any patron.

(2) Gassy starters should not be used.

Remedy :

The method of handling gassy milk or curd is as follows:

(1) If it is known that the milk is gassy, use a safe

amount of clean commercial starter.

(2) Ripgu the milk a trifle more before adding the rennet.

(3) After cutting, stir the curd till the whey around it

shows at least 0.15 per cent of acidity before heating.

(4) Heat slowly. Take 30 to 60 minutes.

(5) Care should be taken to have the curd not too firm

in the whey before the acid begins to form. The
acidity is a valuable guide at this time.

(6) A little more acidity should be allowed to develop

before removing the whey. About 0.32 per_cent
after all the whey is off is sufficient.

(7) Should the curd float, remove the whey to such an Y ^^'^^'

extent that it can not float. ^ "^^

(8) Pile gassv curd before and after milling. ^^»^'^^*^

(9) After milling, the curd should be thoroughly stirred

and aired before piling. The pressure causes the
small pieces to become very thin. After the piling

DEFECTS IN BODY AND TEXTURE 125

and airing have been repeated a few times at inter
vals of 15 to 20 minutes, most of the gases should
have escaped. The pm-holes will then have be-
come flattened and present a "dead" appearance.

(10) The whey running from the curd at this time should

show 1.2 per cent of acidity.

(11) Cool the curd well before putting m press

(12) Press for 48 hours if possible

(13) Ripen in a cool place

GREASY TEXTURE

This is indicated by the presence of free fat in the
mechanical holes in the cheese. The surface of the
cheese is usually greasy. This condition is most
common in spring and in times of drouth.

Cause :

^1) Allowing separation and hardening or drying of cream
on milk before manufacturing, in factories that
do not take milk on Sunday, the trouble is always
greatest on Monday.

(2; Abnormal proportion of fat to casein in milk in times
of drouth (p. 164).

(3) Heating milk too high or too long before adding

rennet .

(4) Handling curd too roughly.

(5) Piling curd too much.

(6) Maturing curd at high temperature.

(7) Using a mill that bruises the curd.

(8) Ripening cheese at high temperatures.
Prevention :

(1) Make up the milk daily, or take pams to keep the

cream stirred in, to prevent formation of dry lumps
that cannot be worked back perfectly into the milk.

(2) Cut and stir the curd very carefully while soft.

(3) Do not pile the curd more than two la^^ers deep.

(4) Do not heat the milk or curd too high. Be sure of the

accuracy of the thermometer used.

(5) Use a mill that cuts the curd without squeezing the

fat from it. The knives should go against the curd
and not the curd against the knives.

(6) Apply the salt soon after milling and mature the curd

after salting.

(7) Ripen the cheese in a cool room.

120 SCIENCE AND PRACTICE OF CHEESE-MAKING

Remedy :

(1) Rinse the curd with water at 90° F. before salting.

Then use a trifle more salt.

(2) Cool the curd before putting in press.

(3) Use large, clean press-cloths to insure the formation

of a good rind.

(4) Use sufficient hot water at the time of dressing the

cheese

FISH-EYE TEXTURE OR YEASTY CHEESE

This is indicated by holes or slits resembling the eye
of a fish. (Fig. 30.) This is usually accompanied
by a bitter flavor. The first indication of this tex-
ture is the formation in the cheese of a number of
small pin-holes surrounded by white rings. These
gradually enlarge until the characteristic slit-like

FIG. 30 — TYPICAL ILLUSTRATION OF THE SLIT-LIKE HOLES

FORMED IN A "yEASTY'' CHEESE

openings are formed. Usually they are most notice-
able near the rind, but in advanced stages extend
throughout the whole cheese. If present in colored
cheese, the color may become badly mottled as the
cheese ages. When the cause of this trouble is
present in milk, there is a bitter taste, which be-
comes more pronounced as the acidity of the milk
increases.

DEFECTS IN BODY AND TEXTURE 1 27

Acidity usually appears in the milk quite slowly, even
after the curd has been first cut. When the formation
of acid once starts, it increases very rapidly. This is
usually during the interval when the whey is removed.
The acid increases rapidly and the curd tends to
become soft or mushy. In the cheddaring process the
curd may become more or less filled with large, shining
openings, resembling gas-holes. After milling, the
curd is usually very slow to contract and, in severe
cases, may soften and lose its body. Frequently yeasts
are accompanied by gas-producing bacteria and, when
this combination is encountered in cheese-making, it
is very difficult to make cheese of passable quality.
Whey from such cheese, when whey tanks are not
frequently cleaned, may appear to boil, as though over
a fire.

Cause :

Yeasts which gain entrance to milk. They have been tuund
on hay-dust, leaves of trees, in unclean cellars, and in whey-
tanks.

(1) In cheese-factory work, the whey tank is the great

source of germ contamination.

(2) Allowing milk to be exposed to the dust of stables

after milking (p. 6).

(3) Keeping milk too warm after placing it in the cans.

Prevention :

(1) After milk is drawn, it should immediately be taken

into a clean atmosphere and cooled to 60° F., and
better to 50° F.

(2) Whey-tanks should be cleaned and scalded twice

a week, at least, and, better still, every day.

(3) All the whey should be pasteurized.

(4) All cans and utensils used m carrying milk should be

thoroughly cleaned and scalded.

Remedy :

When it is known that yeast -infected mitW has been re-
ceived, it should be treated m the following way:

[28 SCIENCE AND PRACTICE OF CHEESE-MAKING

(1) A good commercial stailer should be used.

(2) The rennet should be added when the milk is at such

a stage of ripeness that there will be time to firm
the curd m the whey before too much acidity has
developed.

(3) Use a higher temperature for heating. Generally

about 2° F. higher is sufficient.

(4) Remove the whey with as little acidity as is necessary

to mature the curd properly m cheddaring. it a
good starter has been used, an acidity of 0.24 per
cent, after the whey is all removed and the curd
packed, should be sufficient.

(5) Stir the curd well at the time of removing the whey.

(6) Do not pile the curd high in cheddaring unless gas is

present .

(7) Mill the curd early and air well immediately after.

(8) Should the curd become mushy after milling, apply

one-half the amount of salt to be used. Then m
about an hour, or as soon as the curd has shrunken
and the holes have closed, apply the balance of the
salt.

(9) Curing at low temperature helps to check the slit

formation and the bitter flavor.

CHAPTER XIII

Defects in Color and in Finish

PALE OR ACID-CUT COLOR

This term refers to the Hghter color of portions
of cheese (p. 89).

Cause :

(1) The development of too much acid, wmcn bleaches

or renders paler the color ot the curd.

(2) Failure to firm the curd m the whey early enough.

(3) Using large amounts of starter.

(4) Using poor cheese-colormg.

Prevention :

(1) Have the curd firmed m the whey beiore the ac.dity
has developed to more than 0.18 per cent.

(2^ Cheese should be colored to suit the market for which
it IS intended.

Remedy:

(1) The best place and time to produce a bright, even

color m the curd is in the whey, while the whey is
being removed. From the time the whey has
reached the level ot the curd till it is all removed,
the curd should be well stirred. By watching the
curd during this handling, the color can be seen to
develop rapidly. This is due to the breaking of the
film of moisture which surrounds each piece of curd.

(2) Allow the curd to stand some time after salting before

putting in press.

MOTTLED COLOR

This means an uneven color, most noticeable in
colored cheese.

129

130 SCIENCE AND PRACTICE OF CHEESE-MAKING

Cause :

(1) An uneven development of acid and moisture in the

curd.

(2) Uneven cutting, leading to an uneven contraction of

the curd when heated in the whey.

(3) Neglecting to strain the starter when lumpy.

(4) Adding the starter after adding the cheese-color.

(5) Uneven piling and maturing of the curd

(6) Use of poor cheese-color.

(7) Mixing the curd from different vats.

(8) Lumpy condition ot the curd at the time of removing

the whey, or when salt is applied.

(9) Adding old curd to fresh curd without proper pre-

cautions.
(10) Yeasts. When due to these, the mottling increases
with the age of the cheese.

Prevention :

(1) By uniform cutting, heating and stirring. This is

facilitated by the use of a 5-16-inch, perpendicular,
wire knife, and a 5 -8 -inch, horizontal, steel knife.

(2) Each small piece of curd should be kept separated from

the others while being heated.

(3) The starter should always be strained.

(4) The starter should be added before the cheese-color

is added.

(5) The curd from different vats should not be mixed.

(6) In usmg old curd, it should be placed in the vat about

15 minutes before the whey is removed.

(7) Curd should always be firmed in the whey before too

much acid has developed.

Remedy :

When the curd is badly mottled, there is no remedy that
will make the color uniform. In some instances the color
will become more even as the cheese ages. Preven-
tion is the best remedy.

'a^

SEAMY COLOR

This is a condition in which the outline of each
piece of curd can be easily seen in the cheese.
The uniting surfaces are marked by a pale Hne.
(Fig. 31.)

DEFECTS IN COLOR AND FINISH

131

Cause :

(1) Greasy curds, preventing even absorption of salt

(2) Impure salt.

Prevention :

(1) If curds are very greasy, they should be rinsed ofi

with water at 90° F. just before salting

(2) Only high-grade salt should be used.

Remedy :

There is no satisfactory remedy. Prevention is the only
sure way of overcoming the trouble.

^r^#*ft

FIG. 31 — ILLUSTRATION OF SEAMY COLOR AND ALSO OF LACK

OF PRESSING

RUSTY SPOTS

These are red spots resembling rust, and usually
located in the little pockets of fat that are found
where two pieces of curd come together in pressing.
This is most noticeable in white cheese.

Cause :

(f) Bacillus ruiensis, gaining entrance to milk or curd.
(2) Unsanitary buildings and surroundings. When whey
leaks through the factory floor, the red material

132 SCIENCE AND PRACTICE OF CIIliESE-MAKING

formed by these bacteria may develop. The in-
fectious material may then be carried into the
factory by wind or flies. Once in the factory, every
utensil used in cheese-making soon becomes infected
and the trouble constantly increases.

Prevention :

(1) Keep everything used in the factory absolutely clean.

(2) Do not allow the factory floor to leak. Cement floors

are the most sanitary.

(3) Keep the drain and drain-pipes clean.

(4) Use screen-doors and windows during fly time.
Remedy :

(1) The only way to get rid of this trouble is by a

thorough cleaning and disinfection of the factory
surroundings and of all utensils-.

(2) The starter, if one is used, should be renewed.

METHOD OF CLEANING AND DISINFEC-
TION

(1) Wash all utensils with a brush, hot water, and wash-

ing-powder, and put them into the large milk- vat.

(2) Put a cover over the vat and turn live steam into it.

(3) Steam the utensils for at least one-half hour.

(4) If the drains are dirty, clean them with hot water

and washing-powder. Then steam them for at least
20 minutes.

(5) If the ground, surrounding or under the factory, is

infected, have it covered with lime or fresh earth.

(6) The inside walls, cheese-shelves, and all wood-work

should be washed with a hot solution of bichlorid
of mercury (corrosive sublimate). This is made by
dissolving 7 5 grains of bichlorid of mercury in one
pint of water. Handle this substance with care and
apply this solution with a brush or broom, since it
is a powerful poison.

DEFECTS IN FINISH

This includes anything that detracts from the ap-
pearance of a cheese. As a rnlc, such defects are
due to carelessness on the part of the cheese-maker.

DEFECTS IN COLOR AND FINISH 1 33

UNCLEAN SURFACES
Cause :

(1) Placing cheese on unclean or moldy shelves in the

curing-room.

(2) Using dirty hoops or handling the cheese with dirty

hands.

Prevention :

(1) Wash the shelves after each shipment of cheese leaves

the factory. Use a brush, hot water, and some good
washing-powder that will remove grease. Place the
shelves in the sunlight to dry.

(2) Cheese -hoops should be clean. So should the hands

of the maker.

CRACKED RINDS

These are openings in the side or ends of the cheese.
They are unsightly and allow cheese-flies and molds
to enter.

Cause :

(1) Too much acid.

(2) Greasy curd.

(3) Use of hard press-cloths. /

(4) Lack of pressing.

(5) Wrinkled bandages.

(6) Too dry an atmosphere in curing-room.

Prevention :

(1) Avoid excess of acid in making cheese (p. 53).

(2) Rinse greasy curd with water at 90° F. before salting.

(3) Press-cloths can be softened by soaking in a weak

solution of sulphuric acid.

(4) Press the cheese longer before dressing and have the

bandages well pulled up.

(5) The curing-room atmosphere should show 80 per cent

humidity.

Remedy :

(1) Press the cheese again after washing with warm

water. If this fails,

(2) Paraffin the cheese.

134 SCIENCE AND PRACTICE OF CHEESE-MAKING

MOLDY SURFACES

This condition is familiar. . The formation may be
of several colors.

Cause :

The growth o^ molds is due to

(1) Too much moisture in the air.

(2) Too high temperature.

(3) Insufficient circulation of air.

(4) Lack ot cleanliness m curing-room.

Prevention :

(1) Curmg-rooms should be so equipped that the temper-

ature and moisture can be controlled.

(2) Good circulation of air should be provided.

(3) Curing -rooms should be kept clean.

Remedy :

(1) By spraying cheese with formalin, containing 10 per

cent of formaldehyd.

(2) By burning sulphur, 3 pounds to 1,000 cubic'feet of air.

(3) By washing the ceilings, walls, shelves and all wood-

work with a hot solution of bichlorid of mercury,
made by dissolving 7^ grains in a pint of water
(p. 132).

(4) By whitewashing the walls and ceilings

UNEVEN SIZES

CROOKED SIDES

WRINKLED BANDAGES

COLLARS ON PRESS ENDS

All these are common defects in the finish of cheese.

They are found in almost every factory.

Cause :

Such defects are nearly always due to carelessness on the
part of the cheese-maker. The presses may be worn
out or broken, the followers may not fit the hoops, or
too heavy pressure may be applied immediately after
dressing.

DEFECTS IN COLOR AND FINISH 1 35

Remedy :

The only way by which defects m finish may be overcome
is by proper care on the part of the cheese-maker. Very
often cheese buyers pay less money for cheese of a good
quahty when it is poorly finished. If the cheese-maker
has to pay the reclaim, he generally becomes more care-
ful. There is no excuse for badly finished cheese, be-
cause it is withm the power of every cheese-maker to
make cheese with good finish. A poorly finished cheese
IS a disgrace to the man who mad!e it.

Part III

The
Science of Cheese-Making:

The Chemtcaly

Biological and Other Relations

of Milk and Cheese

Relations of the Constituents of Milk to
Cheese.

Relations of Micro-Organisms and En-
zyms to Milk and Cheese.

Changes in Cheese During tne Ripening
Process.

CHAPTER XIV

The Constituents of Milk

The following constituents of cow's milk are of
special importance in cheese-making:

(i) Fat J'^^'^

(2) Casein J- ^^

(3) Milk-sugar ^' ^^

(4) Salts -^^ ^^ ^^ .

(5) Enzyms j^^^'^*^^^^^''<^a<^^/^^'^tfif*^^<'-

If this list of milk constituents is compared with
a complete statement of the composition of milk, it
is noticeable that water and albumin are omitted.
There are good reasons for such omission.

So far as the process of cheese-making and the
character of the product are concerned, the amount
of water in normal milks requires no special con-
sideration. Slight variations in conditions of the
operations of cheese-making affect the percentage
of water in cheese much more than the variation of
the percentage of water in normal milks. While
dilution of milk by water beyond a certain propor-
tion decreases the rapidity and completeness of
rennet action (p. 307), the amount of water in dif-
ferent normal milks does not vary enough to exert
any such retarding influence that is appreciable, so far
as our observations go.

Milk-albumin calls for little or no study in cheese-
making, since it remains in solution during the

I./'

140 SCIENCE AND PRACTICE OF CHEESE-MAKING

cheese-making process and passes out, for the most
part, with the whey. Numerous attempts have been
made to recover in cheese all or most of the albumin
present in milk, but we know of no case which has
resulted in making a product like normal cheddar
cheese in its properties.

MILK-FAT

Milk- fat, also known as butter-fat, is not a single
chemical compound, but is a somewhat variable
mixture of several different compounds called
glycerids. Each glycerid is formed by the chemical
union of glycerin as a base with some organic acid
or acids of a particular kind (butyric, palmitic,
oleic, etc.). Under the action of certain kinds of
micro-organisms, milk-fat undergoes decomposi-
tion, forming among other products free butyric acid,
which is the compound responsible for the offensive
flavor of rancid cheese and butter.

Fat-globules in milk. — Milk-fat is present in milk,
not in solution, but suspended in the form of very
small, transparent globules. The globules vary in
size, the smaller being more numerous than the
larger ones. The average size of fat-globules in
milk is somewhat larger than one ten-thousandth '^^/ ^
of an inch in diameter. Contrary to what has been
formerly taught, the fat-globules of milk have no
special kind of covering, but are simply minute
particles of fat, floating free in milk in the form of
an emulsion. Skim-milk and whey contain few
globules, as compared with normal milk, while
cream, of course, contains many more than normal

CONSTITUENTS OF MILK I4I

milk. Even in butter and cheese, the fat-globules
of the milk preserve their individuality to a large
extent.

MILK-CASEIN

Milk-casein is of special importance in connection
with cheese-making because the conversion of milk
into cheese is dependent upon the peculiar proper-
ties of casein. This constituent of milk, in an im-
pure and changed form, is most commonly familiar
as the solid, white substance, called curd, which forms
in milk when it sours. It is also familiar as a prom-
inent constituent of separator-slime, and in this form
is not materially changed from the condition in which
it exists in milk.

Composition of milk-casein. — Casein, as it exists
in milk, is a ver); complex chemical compound, be-
longing to a general class of nitrogen-containing com-
pounds known as protein, and to a special subdivision
called phosphoprotcins. Its elementary composition is
about as follows .

Carbon 53-00 per cent

Oxygen 22.70 per cent

Nitrogen i5-7o per cent

Hydrogen 7.00 per cent

Phosphorus 0.85 per cent

Sulphur 0.75 per cent

The presence of phosphorus in casein is one of
its distinguishing chemical features, but in what
particular form of combination the phosphorus ex-
ists is not known at present. Casein in milk does

142 SCIENCE AND PRACTICE OF CHEESE-MAKING

not exist as an uncombined protein, but is, accord-
ing to the best evidence available, in combination
with some form of calcium. Three general views
have been held in regard to the relation of calcium
(lime) compounds to milk-casein: (i) That
milk-casein is in the form of calcium casein, being

j combined with about 1.50 per cent of calcium oxid;

r. (2) that casein is combined directly with calcium
phosphate; (3) that the compound calcium casein
is also in combination with calcium phosphate.
Some facts appear to indicate that the calcium
casein of milk is a form containing 2.4 per cent of
calcium oxid. It has been well established that
casein forms compounds with calcium, but which
particular form of combination exists in milk, as
milk-casein, we cannot yet regard as settled beyond
question.

Physical condition of casein in milk. — For a long
time casein was believed to be in solution in milk
and is still held to be so by those who have ignored
the evidence to the contrary. Some have held that
it was in a state of semi-solution. The view which
must now be regarded as representing the tfuth be-
^•T^/if/yQj^^j all doubt is that casein exists in milk in the
form of extremely minute, gelatinous particles in
suspension. The evidence which proves the cor-
rectness of this view is threefold : ( i ) While the
solid particles of casein are so small that they easily
pass through the pores of fine filter-paper, they do
not go through the finer pores of unglazed porcelain
(like the Chamberland filter) nor through animal
membranes. It is thus possible to strain out casein
from the soluble portions of the milk in quantities

CONSTITUENTS OF MILK I43

sufficient to see and examine. (2) Casein is sepa-
rated from milk by centrifugal force, being de-
posited as a film on the surrounding walls of the
centrifuge. By whirling milk for a number of
hours, practically all of the casein can thus be sepa-
rated from the milk. It is thus that it is deposited
on the walls of the bowl of a centrifugal separator
as separator-slime, in which the casein, in a gelat-
inous form, is mixed with dirt and other bodies.
(3) These two preceding methods of proofs should
be sufficiently convincing in regard to the insoluble
condition of casein in milk; but the latest method
removes all possibility of doubt. Within the past
few months, an article has been published by
Kreidl and Neumann, of Vienna, giving results of
work done by them in studying milk by what is known
as "ultramicroscopic" examination. This method en-
ables one to see very much smaller objects than can
be seen by the usual methods of microscopic work.
These investigators were able to see the actual par-
ticles of casein swimming in milk, to treat them with
reagents and to observe their various transformations.
Their study included the milk not only of cows, but
of other animals.

Action of acids upon milk-casein. — Milk-casein is
made to appear in milk as a heavy, white solid or
precipitate, in more or less flocculent form, by means
of dilute acjds, even by carbon dioxid under certain
conditions, and also by acid salts. Treatment by
acids changes the chemical and phvsical properties
of milk-casein. The most obvious change is that
of physical condition, the very minute, invisible

144 SCIENCE AND PRACTICE OF CHEESE-MAKING

particles of casein coming together into large, vis-
ible aggregations. The cause of this change cannot
yet be fully explained. It has been usually ex-
plained by saying that acids unite with the calcium
of the calcium casein, and the casein, thus deprived
of its combined calcium, is changed from its con-
dition of finely divided, gelatinous particles into
larger masses and then appears as a solid, heavy
precipitate. This explanation is not entirely satis-
factory, since casein may be obtained in the form of
a precipitate when little or no acid is present. The
effect is probably to be ascribed rather to the forma-
tion of soluble calcium salts by the acid than entirely
to the direct effect of acid upon the calcium of milk-
casein.

X When milk sours in the ordinary way, the lactic
acid, thus formed, acts upon the calcium casein,
two definite changes taking place when sufftcient acid
is present. First, the lactic acid combines with the
calcium of the calcium casein, forming calcium
lactate and calcium-free casein (casein set free from
its combination with calcium). When more lactic
acid forms than is sufhcient to combine with the
calcium, the second change takes place ; the free
casein or coagulum takes up the acid, forming a
mixture which is familiar as the curd of sour milk.
It was formerly believed that insoluble, precipitated
casein combines with a definite quantity of acid,
forming a definite compound; and that, under this
supposition, the curd of sour milk is a compound
known as casein lactate. But more extended, care-
ful, and accurate work has shown that the evidence
was misleading upon which was based the belief

CONSTITUENTS OF MILK I45

that casein unites with definite quantities of acids
to form definite, insoluble compounds. Changes
similar to those occurring when milk sours in the
usual way take place when milk is treated with
other acids, such as hydrochloric, acetic, sulphuric,
etc.

Free casein is insoluble in water, and also in very
dilute acids at ordinary temperatures. The action
of acids on calcium casein and on free casein is
hastened by increase of temperature. Less acid :3
required at higher temperature to precipitate casein.
Casein dissolves easily even in quite dilute acids,
more easily at higher temperatures, forming soluble
compounds which are either combinations of acid
with casein or decomposition products of casein,
according to the concentration of the acid, the tem^
perature and other conditions of treatment.

Action of alkalis on milk-casein. — Casein is acid
in character in that it unites easily with fixed
alkalis, ammonia and alkaline carbonates, forming
salts easily soluble in water. Thus, the curd
of sour milk or fresh cheese can be dissolved by
treatment with dilute sodium carbonate or am-
monia. This fact is made use of in cooking, when
tough, insoluble cheese, such as that often made
from skim-milk, is rendered more easily soluble by
use of baking-soda. An interesting experiment in
this connection is to rub in a mortar some pure
casein, suspended in water, with some calcium car-
bonate. The calcium combines with the casein, and
carbon dioxid gas is given off. The soluble com-
pounds of casein with alkalis are not curdled by
rennet, out are precipitated on treatment with acids.

146 SCIENCE AND PRACTICE OF CHEESE-MAKING

Some of these salts formed by casein with aJ.kaiis
are found in commerce in the form of dietetic and
medicinal preparations.

Action of salts on milk-casein. — Milk-casein may
be precipitated, apparently unchanged chemically,
by saturating milk with common salt, magnesium
sulphate, ammonium sulphate, etc., at ordinary tem-
peratures. Milk-casein is also precipitated by small
amounts of solution of alum, zinc sulphate ai/d
many other metallic salts. Calcium chlorid and
some other salts coagulate casein in milk heated to
95°-ii3° F.

Action of heat on milk-casein. — Heat alone under
ordinary conditions, even at the boiling point of
water, does not coagulate the casein in milk. How-
ever, heated under pressure to 26^°-2S^° F., casein
salts are changed in their properties and casein itself
is coagulated. The browning of milk heated under
pressure is more or less due to changes in casein.
The formation of a peculiar skin (haptogen mem-
brane) on milk heated above 140° F. is largely due
to the calcium casein of the milk and not, as was
formerly supposed, to albumin. The skin itself
contains practically all of the constitutents of the
milk and may be regarded as a kind of evaporated
milk. On removing the membrane, a new layer is
formed and, by removing these one after another,
practically all of the milk can be transformed into
the membrane condition. It appears to be due to
surface evaporation.

Action of rennet on milk-casein. — One of the
most characteristic properties of milk-casein is its
coagulation by the enzym or chemical ferment con-

CONSTITUENTS OF MILK I47

tained in rennet. This property makes possible
the manufacture of cheddar and many other kinds
of cheese from milk. The curd formed by the action
ot rennet is called paracasein or, more properly, cal-
cium paracasein. The coagulation of milk-casein pro-
duced by rennet is quite different from that produced
by acids. Calcium paracasein behaves, in general,
much like casein toward acids and alkalis. The details
of rennet action on milk-casein will be considered more
fully in Chapter XXII (p. 299).

Other changes caused in milk-casein. — Under the
action of chemical reagents, of enzyms and of various
micro-organisms, calcium casein and paracasein
may be changed into a large number of other sub-
stances. Among the compounds and classes of com-
pounds thus formed are caseoses (albumoses),
peptones, amino acids (crystallizable bodies) and
ammonia. These products are never found in nor-
mal milk as it leaves the cow's udder, but may be
present in milk that has stood exposed to air for some
time.

Brine-soluble substance formed from casein. —

When milk is treated with rennet and the curd
is handled in the usual manner followed in cheese-
making, a most interesting change begins to take
place, which becomes especially prominent in the
cheddaring operation (p. 32). The curd changes
into a form which is soluble in a warm solution of 5
per cent brine (common salt) ; at the same time, the
curd forms long strings on a hot iron and acquires the
peculiar texture of the cooked meat of a chicken's
breast, with a characteristic velvety mellowness of feel-
ing and glistening, silky appearance. These changes

148 SCIENCE AND PRACTICE OF CHEESE-MAKING

are due, apparently, to the formation of this brine-
soluble substance. More or less of this peculiar
substance remains in the cheese indefinitely. For
example, in a cheese two-and-one-half years old,
the portion of the cheese insoluble in ether (fat)
and in warm water consisted entirely of this brine-
soluble substance. On being warmed, it could be
drawn out in strings over a yard long. (Figs. 32
and 3S')

FIG. 32 — BRINE-SOLUBLE FIG. 33 — STRINGS OF BRINE-
CHEESE PROTEIN WARMED SOLUBLE PROTEIN OF
AND FRESHLY DRAWN CHEESE SUSPENDED AND
OUT IN A STRING SEV- DRIED. STRINGS ABOUT
ERAL FEET LONG FOUR FEET LONG

MILK-SUGAR

Milk-sugar, also called lactose, is present in cow's
milk in solution. In general composition, it re-
sembles ordinary sugar, but it is less sweet and
if ess soluble in water; however, it diflfers much from

CONSTITUENTS OF MILK I49

ordinary sugar in its chemical behavior and espe-
cially in its relations to various ferments. The
amount of sugar in milk varies from below 4 to
over 6 per cent and averages about 5 per cent.
Variation in the amount of sugar in different nor-
mal milks has little interest in connection with the
operations of cheese-making for the reason that
there is always an abundance for cheese-making
purposes. The milk-sugar passes largely into the
whey in the cheese-making process and forms a
large percentage of the solids in whey. The milk-
sugar of commerce is usually prepared by evaporat-
ing whey and purifying the impure product first
obtained. The importance of milk-sugar in cheese-
making depends on the fact that it is easily con-
verted into lactic acid by certain forms of bacteria.
In the making of cheddar cheese, only a small pro-
portion of the sugar is changed into lactic acid during
a considerable part of the process, but one per cent or
more is so changed by the time the curd is salted. In
cheese made from sour milk, such as cottage cheese,
and in starters used in cheese-making, somewhat
more than one-fourth of the milk-sugar is changed
and there is formed in such cases about 0.7 or 0.8
per cent of lactic acid. When milk or whey is
allowed to stand for some time at ordinary tem-
peratures, over I per cent of lactic acid may
be formed. Hence, sour milk or whey, when two
or three days old, usually contains only 3.5 to 4
per Cent of milk-sugar. In cheddar cheese made
under normal conditions, we never find any un-
combined or free lactic acid, since it combines with
calcium of certain calcium salts in the milk to form

150 SCIENCE AND PRACTICE OF CHEESE-MAKINC

calcium lactate, a compound which is neutral
(neither acid nor alkaline), and which does not
taste sour. Under the usual forms of fermentation,
milk-sugar forms small amounts of other com-
pounds in addition to lactic acid. The sour smell
of whey and of sour milk is not due to free lactic
acid, since pure lactic acid has practically no odor,
but is caused by some of the other fermentation
products formed, the exact nature of which is not
fully known.

THE SALTS OF MILK

The salts of milk, commonly represented by the
term *'ash," are present in only small amounts, but
they have extremely important relations to the
process of cheese-making. Our knowledge of these
compounds is very incomplete. The salts of milk
are commonly spoken of as the ash or mineral con-
stituents. This conception is somewhat misleading,
because the materials appearing in the ash of milk
are, to some considerable extent, combined in or-
ganic compounds, instead of existing in milk as
separate inorganic bodies in the form in which they
appear in the ash. The ash, therefore, represents
in amount more than the so-called mineral con-
stituents of milk and less than the salts of milk.
While the average amount of ash in milk is about
0.7 per cent, the amount of salts is probably much
nearer 0.9 per cent. To illustrate this point in more
detail, the citric acid which is present in milk in
the form of citrate salts does not appear at all
in the ash, since it is destroyed in burning the milk
to obtain the ash. In cheddar cheese the ash, not

CONSTITUENTS OF MILK I5I

including the salt added in cheese-making, rep-
resents the salts of the milk even less accurately
than in milk. In cheese, we have a considerable
amount of calcium lactate, but, in obtaining the ash
of cheese, the lactic acid portion is destroyed and so
does not form a part of the ash. The percentage
of ash in green cheese due to constituents obtained
from the milk is usually between 2 and 3 per cent,
varying, of course, with the amount of whey retained
in the cheese.

In milk, a portion of the salts is present in
soluble, and a portion in insoluble, form. The fol-
lowing portions of the salts of milk are present in
solution : Sodium, potassium, chlorine, and citric
acid compounds ; amounts of phosphoric acid in
the form of combined phosphates varying in dififer-
ent milks from 45 to 65 per cent of the total phos-
phoric acid present; 25 to 45 per cent of the calcium
(lime) ; and over 50 per cent of the magnesium.
In what specific forms of compounds these ele-
ments are present in milk is not known and the
problem is a difficult one to solve. The sugges-
tion has been made by Soldner that something like
the following arrangement may be supposed to
exist:

Percentage of the total
Compounds salts in milk

Calcium citrate 23.6

Mono-potassium phosphate 12.8

Sodium chlorid 10.6

Potassium chlorid 9.2

Di-potassium phosphate 9.2

Tii-calcium phosphate 8.9

Di-calcium phosphate 7 .4

Potassium citrate 5.5

Calcium oxid in casein 5.1

Magnesium citrate 4.0

Di-magnesium phosphate 3.7

152 SCIENCE AND PRACTICE OF CHEESE-MAKING

Whether this suggested distribution of com-
pounds among the salts of milk is near the truth
or not, it emphasizes the fact that the matter is
one of no little complication. Some investigators
believe that the calcium phosphate exists entirely as
tri-calcium phosphate; others, as the di-calcium com-
pound, probably on the basis of better evidence. The
presence of soluble acid phosphate and, probably, of
acid citrate also, accounts for a part of the acidity of
fresh milk.

When milk is heated, the amount of soluble calcium
i salts is decreased as the result of being changed to

f insoluble forms.
♦ The presence of soluble calcium salts in milk is

f essential to the coagulation of milk by rennet-extract
(p. 306).

Acidity of milk. — In this connection, we will call
attention to the acidity of fresh, normal milk. Milk
in which lactic acid has had no chance to develop has
the power of neutralizing alkalis and in that respect
behaves like a solution containing acid.

The acidity of fresh milk varies with a number of
conditions, such as ( i ) the milk of the same ani-

' mal at different times, (2) the milk of different
cows, and (3) with the stage of lactation, being
highest at the beginning of lactation and gradually
decreasing with the advance of the lactation period.
The acidity ot fresh normal milk is caused by no
one substance, but is due to the presence of (i)
acid phosphates, (2) citrates and (3) casein. It
has been found to vary widely, from below 4 to over
10, expressed as cubic centimeters of one-tenth
normal alkali, but in most cases it is between 7
and 9.

CONSTITUENTS OF MILK 1 53

Lactic acid begins to be formed in milk soon
after it is drawn, if the milk is not kept below 50°
F. By the time milk reaches the factory, the nor-
mal acidity of the milk is usually increased about
0.05 to o.io per cent, corresponding to a total
acidity of 0.12 to 0.18 per cent. In warm weather ^
the acidity often exceeds 0.20 per cent in the case of
some herds. The increase of acidity over that ex-
isting in fresh normal milk is an indication of the
temperature at which the milk is kept and also of
the cleanliness observed in milking and in caring for
the milk and the dairy utensils with which the milk
comes in contact (see p. 4). An acidity equivalent
to 0.20 per cent of lactic acid in milk when received
at the factory is regarded as the danger line for ched-
dar cheese-making. Generally, only a part of the
milk taken to a cheese-factory will exceed this limit,
so that the average for the day may be considerably
below the 0.20 per cent limit.

MILK-ENZYMS

Enzyms are chemical ferments ; they have the
power to produce changes in other substances with-
out themselves undergoing change. Enzyms are
the products of living cells. According to recent
views, normal milk is not to be regarded as an in-
active fluid, but possesses certain properties char-
acteristic of living substances. Normal milk gives
evidence of the presence of several different en-
zyms, among which are those called (i) diastase,
(2) galactase, (3) lipase, (4) catalase, (5) peroxi-
dase and (6) reductase. The subject has not been
sufficiently studied to enable one to make anything

154 SCIENCE AND PRACTICE OF CHEESE-MAKING

like a clear or satisfactory presentation. It is quite
probable that some of these enzyms, now described
under different names, are the same or are mix-
tures. The quantity of these substances is so ex-
tremely small and the methods of separating them
in pure form are so imperfect that their study pre-
sents peculiar difficulties. One of the main prac-
; tical uses to which enzyms in milk have been put
' depends upon the fact that their presence serves to
distinguish unheated from boiled milk, because the
enzyms are all destroyed by heat. We shall not
consider these substances in detail ' because, so far
as we now know, most of them are not concerned
in cheese-making. Galactase is the only one of special
interest in this connection. This was discovered at
the Wisconsin experiment station in 1897 and has
received considerable attention in connection with
studies of milk and cheese. We shall consider this
enzym in more detail later (p. 297).

CHAPTER XV

Conditions Affecting Proportions of
Constituents in Milk

In studying- the composition of milk from dif-
ferent cows or herds, one of the first facts noticed
is that the same constituents vary in amount more
or less widely in different milks. This fact is of
the highest importance in studying the relations
of milk to cheese-making. As a foundation for
a more detailed consideration of these relations of
milk, it seems desirable that we should study with
some degree of fullness the more important condi-
tions which cause variation in the amounts of
constituents of milk. Those constituents of great-
est interest to us which vary most are fat and
casein. Milk-sugar and salts vary only slightly
as compared with the amount of variation in fat
and casein. We shall find it to be a matter, not
only of interest, but of practical importance, to study
the extent of these variations and their causes,
and also to learn to what extent different influences
affect the relation of fat to casein. As we shall
show later (p. i86), the percentages of fat and
casein in milk largely determine the yield of cheese ;
while the proportion of these two constituents, relative
to each other, determine the composition (p. 231)
and to a considerable degree, the quality of cheese

(p- 243).

155

156 SCIENCE AND PRACTICE OF CHEESE-MAKING

AMOUNT OF FAT IN MILK

The percentage of fat in normal milk varies
greatly, much more than any other constituent,
especially if we consider single milkings of individ-
ual cows. In connection with the manufacture of
cheese, we are more particularly interested in
knowing the percentage of fat in the milk of dif-
ferent herds of cows rather than in that of single indi-
viduals. In the case of single herds of cows, such
as are common in the dairy region of New York
state, the lowest percentage of fat -found on any
one day, as the result of special investigations,
was 2.90; the highest, 5.50, v/hich occurred late in
the season (October). Taking the average of dif-
ferent herds of cows for an entire cheese-factory
season (April to November), the lowest percentage
of fat was 3.31 and the highest, 4.31., In the case
of cheese-factory milk, consisting of a mixture of
the milk of different herds, the lowest percentage
of fat found was 3.04 and the highest, 4.60. The
average percentage of fat in mixed factory milk
for an entire season is about 3.75 ; and this average
has been found to vary only slightly in different
factories and in different seasons. The Wisconsin
experiment station reports 3.64 as the season's
average percentage of fat in the milk of 347 fac-
tories. In the case of individual factories, a sea-
son's average as low as 3.20 per cent is given. The
lowest percentage of fat in the milk of any single
herd for a single day's milk is given as 2.30, while
the highest reported is 5. Results reported in Can-
ada appear to indicate a lower percentage of fat in
milk than in the case of New York.

VARIATIONS OF MILK CONSTITUENTS 1 57

While many conditions cause the percentage of fat
in milk to vary, we will notice only three as of special
importance in connection with cheese-making: (i)
Breed, (2) stage of lactation, and (3) change from
barn to pasture.

Influence of breed of cow^s on fat content of milk.
— The influence of what is known as breed upon
the composition of cow's milk has been long recog-
nized and extensively studied in a general way,
but only in a comparatively limited way in its rela-
tion to cheese-making. It is largely owing to this
influence that we find the milk of one country dif-
fering from that of another, or the milk of one
section of a country differing from that of another
section. For example, the average percentage of
fat in milk in Germany and Holland is fully one-
half per cent lower than in New York state, and
probably in the United States at large, because the
prevailing breeds of cows there are those producing
milk comparatively low in fat. The results of
recent tests go to show that in Canada the milk
in Quebec province contains more fat than does
that of Ontario, since in the former the native
Jerseys are the predominant breed, while in the
latter, Holstein-Friesians, Ayrshires and Short-

PERCENTAGE OF FAT IN MILK OF DIFFERENT BREEDS OF

cows

Name of breed Per cent of fat in milk

Holstein-Friesian 3.26

Ayrshire 3.76

American Holdemess 4.01

Shorthorn 4.28

Devon 4. 89

Guernsey 5.38

Jersey 5.78

158 SCIENCE AND PRACTICE OF CHEESE-MAKING

horns prevail. The foregoing table represents aver-
ages in the case of three to six individuals of each
of seven different breeds for an aggregate of four
to twenty lactation periods with each.

Influence of stage of lactation on fat content of
milk. — From the time a cow "cgmes fresh in milk"
up to the time she becomes ''dry," the composition
of the milk undergoes gradual changes, which are
quite independent of other factors. The period of
lactation varies in length with different individual
cows, but, for practical purposes, lasts about 10 to
12 months. The changes observed in the percent-
age of fat during the progress of the lactation
period are quite marked and fairly regular, with-
out reference to individual or breed. The colos-
trum, which is the secretion produced by a cow
soon after calving, is very different in composition
from normal milk and is not considered at all in
our discussion of the constituents of milk, because
it has no interest for us in this connection. The

VARIATION OF PERCENTAGE OF FAT IN MILK WITH

ADVANCE OF LACTATION

Month of lactation

Per cent of
fat in milk

Percentages in

comparison with

first month

1. .

4.30
4.11
4.21
4.25
4.38
4.53
4.57
4.59
4.67
4.90
5.07

100.0

95.6

97.9

98.8

101.9

105.3

106.3

106.8

108.6

114.0

118.0

i^IATIONS OF MILK CONSTITUENTS

159

figures presented in the table on page 158 represent
the monthly averages of nearly 100 different lactation
periods.

In studying this table, we notice that the per-
centage of fat decreases in the second month, as
compared with the first, and then begins to in-
crease, continuing to increase from month to month
during the entire period of lactation. The rate of
increase is more rapid during the last two or three
months than previously. Such behavior appears
to be the general rule. Variation from the com-
parative degree of regularity observed in the fore-
going table may, of course, appear in the case of
individuals.

It will be a matter of more immediate interest to
consider the influence of advancing lactation upon the
percentage of fat as observed in the case of milk
used at cheese-factories. In general, dairymen
have their cows begin the period of lactation in
March and April, so that milk taken to a cheese-
factory represents, during the season, stages of the
lactation period extending from about the second

VARIATION OF FAT IN CHEESE-FACTORY MILK V^ITH

ADVANCE OF LACTATION

Month

April

May

June

July

August. . .
September
October. . .

Per cent of fat
in milk

New York
3.43
3.58
3.64
3.62
3.84
3.98
4.23

Wisconsin
3.48
3.49
3.50
3.55
3.63
3.84
4.08

Percentages in com-
parison with first nionth

New "^'c

.rk

Wisconsin

100.0

104.4

100.3

106.1

100.6

105.5

102.0

112.0

104.3

116.0

110.3

123.3

117.2

l60 SCIENCE AND PRACTICE OP CHEESE-MAKING

to the eighth months. Cows kept under ordinary
farm conditions are subject to greater variations
of external influences than those used in the investi-
gation represented by the figures in the preceding
table. The figures in the table on page 159 repre-
sent results secured in New York and Wisconsin.

Influence of change from barn to pasture upon
the percentage of fat in milk. — In the course of a
study of cheese-factory milk in New York, it was
noticed that, under certain conditions, a marked
change in percentage of fat in milk took place.
Each year while the study of factory- milk was carried
on, it was observed that about the middle of May.
there was a considerable increase in the percentage
of milk-fat, accompanied by an increase of other
solids and also by a larger yield of milk. Thus,
during the first half of May, the milk contained
3.46 per cent of fat and, during the second half,
3.70 per cent. These results are in agreement with
those reported by the Vermont and Wisconsin ex-
periment stations and also by the Ontario agricul-
tural college. This question has been more thor-
oughly studied at the Vermont experiment station
than elsewhere and, according to the results ob-
tained during a series of years, the general rule
shows a change like that noticed above, but in some
years little or no change could be observed. A
careful study of all the available facts appears to
justify the explanation that the increased per-
centage of fat in milk under the given circum-
stances was due to a marked change In the char-
acter of the food and environment of the cows,
since they were turned out to pasture about the

variatio:ns of milk constituents i6i

middle of May. Under the known existing condi-
tions of the food and environment of cheese-factory
cows, there was thus a change from dry food of
an indifferent character, mainly straw or poor hay
without grain, to a highly succulent food of a most
palatable kind. It is probable also that the changes
in the environment of the cows from confinement
in barn and yard to the freedom of pasture exercised
a beneficial, physiological influence.

AMOUNT OF CASEIN IN MILK

The percentage of casein in normal milk varies
quite widely, though much less than in case of
milk-fat. In the single milkings of individual cows,
we have found casein as low as 1.59 per cent and
as high as 4.49 per cent. The highest percentages
were found in the case of cows far along in lacta-
tion and giving only small amounts of milk. In
the case of individual herds of cows, the percentage
of casein ranged from 1.79 to 3.02. In the case of
milk consisting of a mixture of the milk of several
different herds, the percentage of casein varied from
1.93 to 3.00.

The conditions which influence variation of casein
in milk, so far as they are of special interest to us
here, are (i) breed, (2) stage of lactation, (3)
change from stable to pasture, and (4) effects of
drouth.

Influence of breed of cov^s on percentage of
casein in milk. — The following results illustrate, in
general, the variation of casein in the milk of different
breeds of cows :

l62 SCIENCE AND PRACTICE OF CHEESE-MAKING

PERCENTAGE OF CASEIN IN MILK OF DIFFERENT BREEDS

OF COWS

Name of breed Per cent of casein in milk

Holstein-Friesian 2.20

Ayrshire 2.46

American Holderness 2.63

Shorthorn 2.79

Devon 3.10

Guernsey 2.91

Jersey 3.03

Influence of stage of lactation on the percentage
of casein in milk. — We will first present results
representing the average of about lOO lactation periods
of individual cows and then the results representing
work done at the New York experiment station in
connection with cheese-factories in New York state,
already referred to:

VARIATION OF PERCENTAGE OF CASEIN IN MILK WITH

ADVANCE OF LACTATION

Month of lactation

Per cent of
casein in milk

Percentages in compari-
son with first month

2.54

100.0

2.42

95.3

2.46

96.8

2.52

99.2

2.61

102.8

2.68

105.8

2.74

108.0

2.80

110.2

2.90
3.01

114.2

118.5

3.13

123.2

According to these results, the percentage of casein
decreases in the second month of lactation, as com-
pared with the first, and then begins to increase, con-
tinuing to increase month by month to the end of the
lactation period. The behavior very closely resembles
that of fat.

VARIATIONS OF MILK CONSTITUENTS

163

Turning now to the results obtained at cheese-fac-
tories, we have the following" data :

VARIATION OF CASEIN IN CHEESE-FACTORY MILK WITH

ADVANCE OF LACTATION

Month

April

May

June

July

August. . . .
September
October. . .

Per cent of
casein in milk

Percentages in compari-
son with first mont-i

100.0
102.2
108.0
106.1
104.3
111.3
122.7

In the foregoing figures, we see that the percentage
of casein in milk increases in May and still more in
June, after which a decrease takes place in July, fol-
lowed by still further decrease in August. There is a
rapid recovery and advance during September and
October. The cause of these variations will be con-
sidered later.

Influence of change from barn to pasture upon
the percentage of casein. — Attention has already
been called to this subject in relation to fat. We now
give corresponding figures for casein. During the
first half of May, the milk contained 2.25 per cent of
casein and during the second half of May, 2.45 per
cent. The same explanation applies as in the case
of increase of fat.

Influence of drouth upon the percentage of casein
in milk. — During a time of severe drouth in New
York, beginning in July and lasting through Au-
gust, with infrequent and insufficient showers, a
marked decrease was noticed in the casein of the
milk, even when the fat was increasing. The ana-

164 SCIENCE AND PRACTICE OF CIIEESE-MAKING

lytical data are given later on p. 168. Under these
conditions, the pasture grasses were badly burned,
most of the dairymen were without supplementary
supplies of food, and consequently the cows suf-
fered a certain degree of starvation. The changes
in composition of milk were accompanied by a
severe shrinkage in yield of milk. Along with this
impaired condition of food supply, the animals
were subjected to the unfavorable effects coming
from excessive heat combined with annoyance of
flies. Cheese-makers often complain of the be-
havior of the cheese made at such times, without
understanding the cause of their difficulty. The
cheese leaks fat badly, does not press together well,
and does not stand up perfectly, although behaving
properly when first made. There is also noticed
an excessive loss of fat in whey. This behavior is
due to an abnormal decrease of casein in relation
to fat, so that the milk and cheese contain an ex-
cess of fat. Cheese-makers at such times are really
dealing with milk which is not normal factory milk,
but which is like normal factory milk to which some
cream has been added. The extreme heat of the
weather, which causes the decrease of casein, also
makes it more difficult to handle such milk in cheese-
making. In the twelfth annual report of the Wiscon-
sin experiment station, attention is called to a similar
condition.

RELATION OF FAT AND CASEIN IN MILK

As we shall see later (p. 231), the relation of
fat and casein in milk is an extremely important
one in connection with cheese-making. At this

VARIATIONS OF MILK CONSTITUENTS

1 6s

point we shall call attention only to the general
relation in different milks and *to the conditions
which influence this relation, leaving the various
application of the facts to later chapters. We have
already noticed the percentages of fat and of casein
in milk and some of the conditions which cause
variation. We now come to consider whether fat
and casein vary alike ; that is, whether fat and casein
have the same relation to each other in milk under
all conditions. We will consider this phase of the
subject under the following divisions: (i) Individ-
uality, (2) breed, (3) stage of lactation, and (4) fresh
pastures and drouth.

Influence of individuality upon relation of fat
and casein. — The results of the work done at the
New York experiment station and elsewhere have
shown that the relation of fat and casein varies greatly
in the milk of different individuals, the variation being
greatest, of course, in the case of single milk-
ings. This fact has been well recognized for 15
years or more and is too familiar even to need illus-
tration.

Influence of breed upon relation of fat and
casein. — The following data are taken from those
already given on preceding pages.

Name of breed

Holstein-Friesian. . . .

Ayrshire

American Holdemess

Shorthorn

Devon

Guernsey

Jersey

Per cent
of fat

3.26
3.76
4.01
4.28
4.89
5.38
5.78

Per cent
of casein

2.20
2.46
2.63
2.79
3.10
2.91
3.03

Parts of casein for
one part of fat

Fat; Casein

0.67
0.6S
0.66
0.65
0.63
0.54
0.52

l66 SCIENCE AND PRACTICE OF CHEESE-MAKING

It is seen that the different breeds represented
separate into two general gronps in relation to the
ratio of fat to casein. In the case of the first five
breeds in the list, this ratio does not vary widely.
The milk containing least fat contains the largest
amount of casein in relation to fat ; but, even though
the percentage of fat in the case of this group in-
creases to 4.89, as in the case of the Devon breed,
the ratio of casein does not diminish greatly. The
Guernsey and Jersey breeds constitute the second
group, the fat being high in amount but the casein
relatively low.

Influence of stage of lactation upon the relation
of fat and casein. — We have already noticed that
the percentage of fat and of casein increases grad-
ually and quite regularly during the period of lacta-
tion. We will now consider the question as to
whether these constituents increase in the same
ratio.

RELATION OF FAT AND CASEIN DURING LACTATION

PERIOD

Month of lactation

Per cent

of fat

Per cent
of casein

Parts of casein for
one part of fat

4.30
4.11
4.21
4.25
4.38
4.53
4.57
4.59
4.67
4.90
5.07

2.54
2.42
2.46
2.52
2.61
2.68
2.74
2.84
2.90
3.01
3.13

Fat : Casein

1: 0.59
1: 0.59
1: 0.58
1: 0.59
1: 0.60

1: 0.59
1: 0.60
1: 0.61
1: 0.62

1: 0.62

1 : 0.62

VARIATIONS OF AIILK CONSTITUENTS

167

These results show a remarkable uniformity in the
ratio of fat to casein throughout the lactation period.
The ratio remains quite constant for seven or eight
months and then increases slightly, remaining the
same during the rest of the lactation period.

It will be of practical interest in this connection to
observe what the relation of fat and casein is during
the season in the case of the mixed milk of many
herds of cows, as obtained at New York cheese fac-
tories

RELATION OF FAT AND CASEIN IN CHEESE-FACTORY

MILK DURING SEASON

Month

April

May

June

July

August . . . .
September,
October. . .

Per cent
of fat

3.43
3.58
3.64
3.62
3.84
3.92
4.23

Per cent
of casein

2.29
2.34
2.47
2.43
2.39
2.55
2.81

Parts of casein for
one part of fat

Fat : Casein

1: 0.67
1:0.65
1: 0.68
1:0.67
It 0.62
1: 0.65
It 0.66

The same fairly uniform relation holds except in
the case of the month of August, when the casein
decreased relative to fat. It is interesting to notice
how closely the relation of fat and casein in cheese-
factory milk agrees with that of the Holstein-Friesian
and Ayrshire types as given in the table on p. 165.
The cheese-factory cows were grade Holsteins and
Ayrshires to a considerable extent

Influence of fresh pastures and of drouth upon
the relation of fat and casein in milk. — Usine the
data already given, we have the following tabular

l68 SCIENCE AND PRACTICE OF CHEESE-MAKING

statement in regard to the influence of turning cows
from barn into pasture about the middle of May:

First half of May. . .
Second half of May.

Per cent

of fat

in milk

3.46
3.70

Per cent

of casein

in milk

2.25
2.45

Parts of casein for
one part of fat

Fat: Casein

1: 0.65
1: 0.66

It is seen that under the conditions indicated,
the fat and casein maintain a relation that is very-
uniform.

Turning now to data obtained during a summer
when extreme drouth prevailed during part of July
and all of August, we have the following results :

EFFECT OF DROUTH UPON RELATION OF FAT TO CASEIN

IN MILK

Month

May

June

July

August . . . .
September
October. . .

Per cent
of fat

3.58
3.59
3.71
4.04
3.97
4.20

Per cent
of casein

2.40
2.33
2.20
2.26
2.47
2.69

Parts of casein for
one part of fat

Fat:

1:
1:
1:

Casein

0.67
0.65
0.59
0.56
0.62
0.64

These results show, for cheese-factory milks, an
abnormal ratio of fat and casein in July, which was
still further from normal in August. In Septem-
ber, when abundant rains came and when, in addi-
tion, dairymen had fodder corn to supplement
pastures with, the ratio became more nearly nor-
mal and still more so in October. From the stand-
point of practical -application, these facts indicate

VARIATIONS OF MILK CONSTITUENTS 169

the necessity for dairymen to guard against the
effects of drouth by making provision for furnish-
ing some form of succulent food then. At such
times, there is an enormous loss due to shrinkage
in yield of milk; and, in cheese-making, there is an
abnormal loss of fat in whey, resulting in decreased
yield of cheese for lOO pounds of milk.

THE RELATION OF FAT AND CASEIN IN
CHEESE-FACTORY MILK

We have seen that the relation of fat and casein
is a variable one, the variations being less wide, of
course, in the case of herd milk than in that of
individual cows, and especially of single milkings
of individuals. But, in the case of averages of
several analyses of milk and in the case of m'ilk
of herds, especially when cows are of one general
type in respect to breed, a certain degree of uniform-
ity exists in the relation of fat to casein. In New
York a careful study was made of the milk of each
of 50 different herds of cheese-factory cows during
one season (May to October), and, as one of the
results, a general relation was noticed between the
fat and casein. In general, it was found that when
the fat in milk increases i.o per cent, there is an
average increase of casein amounting to 0.4 per
cent. This was found to hold quite satisfactorily
when applied in case of ordinary herd milk varying
in fat content from 3 to 4.5 per cent and, in many
cases_, outside of these limits. In milk containing
less than 3 per cent of fat, the casein content is
usually higher in relation to fat than in milk with
more than 3 per cent of fat; while, in the case of

170 SCIENCE AND PRACTICE OF CHEESE-MAKING

milk containing- more than 4.5 per cent of fat, the ratio
of casein to fat is frequently less than in milk con-
taining less than 4.5 per cent of fat. Starting with
milk containing an average of 3 per cent of fat and
a casein content of 2.1 per cent, milk with 4 per cent
of fat was found to contain about 2.5 per cent of
casein on an average.

RULE FOR CALCULATING AMOUNT OF

CASEIN IN MILK

On the basis of the observed general relations stated
above, the following formula was worked out for cal-
culating the percentage of casein in milk when the per
cent of fat is known :

(F — 3) Xo.4+2.i=per cent of casein.

F equals the number representing the per cent of fat
in milk. Expressed as a rule, we have the following:
From the number representing the per cent of fat
in milk subtract 3 ; multiply the result by 0.4 and
then add 2.1. The formula is apt to give results
not quite up to the actual in case of milk produced
nfter the eighth or ninth month of lactation period,
when the casein is usually a little greater in rela-
tion to fat than during the previous stage of the
lactation period. Applied separately to the milk
of 50 herds of cows during the factory season, the
average results for the season are summarized as
follows : ( I ) In 4 cases, the results found by chemi-
cal determination were identical with those given
by calculation; (2) in ^6 cases, the results by cal-
culation were within o.i per cent of those obtained
by the chemical method; (3) in 8 cases the chemi-
cal method gave o.i to 0.2 per cent less than the

VARIATIONS OF MILK CONSTITUENTS I7I

calculated amount; (4) in 2 cases the calculated per
cent exceeded that found by the chemical method to
the extent of 0.23 and 0.25 per cent. It is thus seen
that, taking the entire season's average, 80 per cent
of the results by the method of calculation differed
from those obtained with the chemical method by
less than o.i per cent. The results given below
represent the application of the formula in case of herd
milk:

Per cent of fat

Per cent of casein in mil]

'<., as found b'

in milk

(1)

(2)

Chemical method

Calcvdation

3.25

2.38

2.20

3.31

2.19

2.22

3.42

2.27

3.52

2.30

''.30

3.55

2.34

2.32

3.55

2.18

2.3?

3.63

2.45

2.35

3.63

2.33

2. 35

3.71

2.29

2.38

3.71

2.48

2.38

3.71

2.35

2.3&

3.84

2.44

3.84

2.37

2.44

3.92

2.42

2.47

4.00

2.53

2.50

4.14

2.50

2.56

425

2.51

2.60

4.31

2.37

2.62

For ordinary purposes, where the strictest accti-
racy is not required, the rule can be used with quite
satisfactory results, when applied to herd milks
within the limits specified, and most of our cheest^-
factory milks come within these limits. Of course,
it is readily recognized that, when very accurate,
results are necessary, only a direct determinaticm
of casein by an accurate method can suffice for t)ie
purpose ; and, by an accurate method, is meant one
which can be relied upon to give results within on^-
tenth of one per cent of the truth.

Ratio of

Fat

Casein

0.70

0.68

0.66

0.64

0.62

0.61

0.60

0.59

172 SCIENCE AND PRACTICE OF CHEESE-MAKING

AMOUNT OF FAT AND CASEIN IN ORDI-
NARY FACTORY MILK

In the case of ordinary cheese-factory milk, we may
expect to find the fat and casein run somewhat as
follows :

Per cent of fat Per cent of casein

in milk in milk
3.00 2.10

3.25 2.20

3.50 2.30

3.75 2.40

4.00 2.50

4.25 2.60

4.50 2.70

5.00 2.90

RELATION OF CASEIN AND ALBUMIN IN

MILK

It IS a matter of practical interest in connection
with cheese-making" to know whether, in milk with
a high percentage of casein, there is also a propor-
tionally high percentage of albumin. The higher
the casein, relative to albumin, the greater is the
proportion of cheese-producing constituents. We
will study this question in relation to (i) breed and
(2) stage of lactation. It should be stated that
albumin, as here used, includes all the proteins of the
milk other than casein.

In studying the results, it is noticeable that, m
general, in the case of milk containing a low per-
centage of fat (p. 165), the albumin forms a larger
proportion of the proteins than in case of milk con-
taining a high percentage of fat, when we compare
the milk of different breeds of cows under corre-
sponding conditions. Also, in milks low in fat, the
casein forms a smaller proportion of the proteins

VARIATIONS OF MILK CONSTITUENTS

173

INFLUENCE OF BREED UPON THE RELATION OF CASEIN

AND ALBUMIN

Name of breed

Per cent

proteins

(casein

and

albumin)

Per cent
of
casein

Per cent

of
albumin

Parts of casein
for one part
of albumin

Per cent
ol total

proteins
inform

of
casein

Holstein-Friesian.. . .

Ayrshire

American Holdemess

Shorthorn

Devon

Guernsey

Jersey

Albvunin: Casein

2.84

2.20

0.64

1: 3.4

3.07

2.46

0.61

1; 4.0

3.32

2.63

0.69

1: 3.8

3.43

2.79

0.64

1: 4.5

3.93

3.10

0.83

1- 3.7

3.56

2.91

0.65

1: 4.5

3.68

3.03

0.65

1: 4.7

77.5
80.1
79.2
81.3
73.9
81.7
82.3

than in case of milks higher in fat. Thus, in the
milk of Holstein-Friesian cows, we have the least
amount of fat (3.26 per cent), and the casein forms
a smaller part (77.5 per cent), and the albumin a
larger part (22.5 per cent), of the proteins than in
case of any other breed under discussion. In the
case of Guernsey and Jersey milk, in which the fat
content is highest, the proportion of casein to pro-
teins is greatest (about 82 per cent), while it is least
for albumin (about 18 per cent). In its practical
application, these results mean that, in the case of
Jersey and Guernsey milk, a larger proportion of the
proteins is utilized in cheese-making and a smaller
proportion is lost in whey.

The relation of casein and albumin, as shown by
the following data, is remarkably uniform during
the first eight or nine months of lactation, varying
between 4.1 and 4.2 parts of casein for one of
albumin ; or, stated in another way, the percentage
of total proteins in the form of casein varied from
80.3 to 80.9 and, in the form of albumin, from 19. 1

174 SCIENCE AND PRACTICE OF CHEESE-MAKING

INFLUENCE OF STAGE OF LACTATION UPON THE RELA-
TION OF CASEIN AND ALBUMIN

Month

lactation

Per cent
of Proteins
(casein and

albumin)

Per cent

casein

Per cent

of
albumin

Parts of casein

for one part

of albumin

Albumin: Casein

Per cent of

total

proteins in

form of

casein

3.16
2.99
3.04
3.13
3.25
3.33
3.40
3.47
3.57
3.79
4 04

2.54
2.42
2.46
2.52
2.61
2.68
2.74
2.80
2.90
3.01
3.13

0.62
0.57
0.58
0.61
0.64
0.65
0.66
0.67
0.67
0.78
0.91

4.1
4.2
4.2
4.1
4.1
4.1
4.2
4.2
.4.3
3.9
3.4

80.4

80.9

80.5

80.3

80.5

80.6

80.7
81.2

11,.

79.4
77.5

to 19.7. After the ninth month, the albumin in-
creases relative to casein, the increase being very-
marked in the two closing months of the lactation
periods studied.

In the case of the mixed milk of numerous herds
of cheese-factory cows, we have the following re-
sults :

Month

April.

May

June

July

August

September. .
October. . . .

Per cent

of protein

Per cent

(casein and

albumin)

casein

albumin

Parts of casein
for one part
of albumin

Per cent

of total

proteins in

form of

casein

2.81
3.02
3.24
3.07
3.02
3.20
3.55

Album

2.29

0.52

2.34

0.68

2.47

0.77

2.43

0.64

2.39

0.63

2.55

0.65

2.81

0.74

: Casein

4.4

3.4

3.2

3.8

3.9

3.8

81.5
77. S
76.2
79.2
79.1
79.7
79.2

The proportion of casein in relation to albumin
decreases until July, when a marked increase oc-

VARIATIONS OF MILK CONSTITUENTS

175

curs ; and then the ratio remains uniform during the
rest of the season, which extends approximately
through the seventh or eighth month of lactation.

The general statement has been prominently cur-
rent in literature to the effect that casein and albumin
are present in cow's milk in very constant relative pro-
portions, the amount of casein being five times that of
albumin. In the case of herd milks, we have found
casein varying all the way from 2.6 to 5.6 parts for
one part of albumin. In single milkings of individual
cows, the variations are considerably wider.

AVERAGE COMPOSITION FACTORY MILK

The following figures represent the average
monthly composition of milk as obtained at cheese-
factories in New York state. These data repre-
sent the work of several seasons and are taken
from the records of the New York experiment
station :

Month

Solids

Fat

Casein

Albumin

Sugar
ash. etc.

April

May

June

July

August . . . .
September.
October. . .

Average . . .

11.98

3.43

2.29

0.5?

12.43

3.58

2.34

C.68

12.64

3.64

2.47

0.77

12.52

3.62

2.43

0.64

12.65

3.84

2.39

0.63

12.86

3.98

2.55

0.65

13.50

4.23

2.81

0.74

12.67

3.75

2.46

0.68

5.74
5.83
5.76
5.83
5.79
5.68
5.72

5.78

The following figures show the extreme variaiions
in composition of cheese-factory milk during the
season :

iy6 SCIENCE AND PRACTICE OF CHEESE-MAKING

■

Lowest
per cent

Highest
per cent

Solids

11.47
3.04
1.93
0.47
5.32

13.91

Fat

4.60

Casein

3.00

Albuniin

0.88

SuEfar, ash, etc

5.37

For a more general and, in some respects, more com-
plete discussion of the chemistry of milk, the reader
is referred to "Modern Methods of Testing Milk and
Milk Products," published by Orange Judd Company.

CHAPTER XVI

Functions of MOk Constituents in
Cheese-Making

Having- considered the properties and amounts of
different constituents in milk in connection with
cheese-making, it -is a matter of interest to notice what
particular part each performs in the process or what
particular contribution of value each makes to the
fini-shed product. It will be found that each con-
stituent has a value peculiar to itself in relation to
cheese and the process of cheese-niaking.

MILK-FAT

Milk- fat is the object of solicitous care on the
part of the intelligent cheese-maker, and its pecu-
'liarities have much to do with certain details of
the cheese-making process. Its part in the actual
process of cheese-making is, however, a passive
rather than an active one, since the details of the
operations are governed, to a considerable extent,
by the aim of retaining as much milk-fat as pos-
sible in the cheese and losing the smallest possible
amount in whey. The reasons for keeping milk-fat
in cheese are twofold, (i) on account of its influence
on the yield of cheese and (2) on account of its effect
upon the quality of the cheese.

So far as we know at present, milk-fat contributes
little or nothing to the aroma of normal cheddar

177

178 SCIENCE AND PRACTICE OF CHEESE-MAKING

cheese ; but its chief functions, in relation to quaHty of
cheese, appear to be to give (i) a characteristic mel-
lowness of body, (2) smoothness of feeling, (3) rich-
ness and delicacy of taste, apart from cheese flavor
proper, and (4), in general, palatability. No other
constituent can take its place satisfactorily in perform-
ing any of these offices. Of course, the high value of
milk-fat as a food should not be lost sight of, but this
does not necessarily enter into the question of quality
of cheese as affected by the presence of fat. The
peculiar and exclusive function of milk-fat in giving to
cheese certain desirable qualities can be well appre-
ciated by comparing dift'erent kinds of cheese, equally
well made and differing only in the percentage of fat
contained in them, as, for example, cheese made from
normal milk containing added cream, cheese made from
normal Jersey milk, cheese made from Holstein-
Friesian milk, and cheese made from milk skimmed
in varying degrees, down to separator skim-milk
cheese.

The relation of fat to yield of cheese will be con-,
sidered in detail in the next chapter.

MILK-CASEIN

Casein is the constituent of milk which, on ac-
count of its peculiar action toward rennet-extract
solutions, makes possible the manufacture of ched-
dar and many other kinds of cheese. In the pro-
cess of cheese-making, it performs two specific
functions: (i) In its solidification, its first work is
to imprison the fat-globules in the curd and then
continue to hold them as firmly as possible through-
out the manipulations of cheese-making. (2) Its

FUNCTIONS OF MILK CONSTITUENTS I79

second function is to retain whey in the curd in
desired amounts, while, at the same time, permit-
ting superfluous whey to escape from the mass of
curd. The power of casein to hold moisture is
somewhat like that of a sponge. Special experi-
ments at the New York experiment station have
shown that one pound of dry casein can easily
absorb and hold about one pound and a quarter of
water. Fat has, of course, comparatively little
water-holding power, so that this function falls
almost entirely on casein. It is obvious that this
special work can be done by no other constituent
of milk, and thus casein is recognized as the water-
holder in cheese.

In the finished product, casein, or rather, the
compound formed from it, performs two important
and peculiar functions, (i) It gives to the cheese
firmness and solidity of body under a wide range
of temperature, conditions which are requisite for
its keeping and convenient handling. The casein-
derived product in reality constitutes the firm
framework or skeleton which gives permanence to
the form of the cheese. (2) It furnishes the protein
material in which, it is believed, take place those
changes that result in characteristic cheese flavors,
while, at the same time, it is converted into soluble,
nutritive compounds, which add largely to the value
of the cheese as food. The peculiar properties of
casein when made into cheese are such that its
presence in excess in relation to fat or moisture
causes serious deterioration in some of the proper-
ties of the cheese. For instance, when an excess of
casein is used, as in the case of skim-milk cheese,

i80 SCIENCE AND PRACTICE OF CHEESE-MAKING

the desirable firmness of body becomes objectionable
hardness, unless the conditions of manufacture are
so modified as to hold more whey in cheese, in which
case objectionable properties of another kind are apt
to result.

WATER

As we shall see later, when we come to study
the composition of cheese, water is one of the most
prominent constituents in amount. We have al-
ready indicated why the amount of water in normal
milk has little interest in connection with cheese-
making, but its presence in cheese is of great
interest and the problem of its control in the cheese-
making process is one of the highest importance.
Water performs two chief functions in cheese :
(i) Somewhat like fat, but in a much less satisfactory
way, it influences the character of the body in cheese,
imparting smoothness and a certain degree of mellow-
ness, and (2) it furnishes suitable conditions for the
work of those agents which change insoluble cheese
proteins into soluble forms (p. 353).

In performing the first of these functions, water,
therefore, supplements the work of fat, but cannot
take its place in imparting richness and delicacy of
taste. In the manufacture of skim-milk cheese, an
efifort is usually made to imitate the mellowness of
body characteristic of a cheese made from normal milk,
which is due to fat, by holding in the cheese a large
amount of moisture. In illustration of this fact,
we have examined cheese containing over 50 per
cent of water, the cheese having been made from
separator skim-milk. Unless this large amount of

FUNCTIONS OF MILK CONSTITUENTS l8l

moisture is retained, the cheese is hard, tough and
unpfelatable. Even in cheese made from normal
milk, the body becomes dry and mealy or crumbly,
if the amount of moisture falls much below 30 per
cent. The higher the fat content of the cheese, the
lower can be the amount of water without impair-
ing the body of the cheese. The temptation is often
strong in making cheese to incorporate 5 per cent
or more of moisture beyond the usual amount, be-
cause water is the only cheese constituent that can
be had free of cost. The aim of cheese-makers
should be so to control conditions of manufacture as
to retain in cheese onlv the proper amount of moisture

(p. 382).

We have already stated that another function of
water in cheese is to furnish conditions suitable for
the work of those agents which convert insoluble
cheese proteins into soluble forms. If the amount
of water is below a certain limit, 25 to 27 per cent,
these changes do not take place and the cheese fails
to become edible.

Some erroneously think that water in cheese is
of a peculiar kind and possesses a special value as
such, — that it is really dififerent from water as we
find it elsewhere. One writer goes so far as to
speak of the water in cheese as ''natural water,"
''natural moisture," as if it possessed some unusual
virtue because it had gone through a cow and
formed a part of milk before going into cheese as
''natural" water. Such a belief is quite without
foundation, because the water in cheese can be
easily separated from the cheese and examined and
is known to possess the usual composition of water

l82 SCIENCE AND PRACTICE OF CHEESE-MAKING

wherever we find it. It is true, of course, that the
presence of water in cheese is masked by the casein
and fat and one of the aims of the cheese-maker is
to conceal it thus as completely as possible; but this
fact has no bearing on the composition or character
of the water itself.

MILK-SUGAR

The only function milk-sugar appears to per-
form in the process of cheese-making is to fur-
nish material for making lactic acid. Lactic acid
does not remain in milk as free or uncombined
acid, but, as fast as formed, it acts upon some of the
salts of the milk, especially insoluble calcium phos-
phate, combining with a portion of the calcium and
forming calcium lactate and soluble or acid calcium
phosphate, an acid salt. There are probably other
salts in milk acted upon, about the details of which
we have not yet obtained complete knowledge. These
soluble calcium salts (calcium lactate, and acid cal-
cium phosphate, including probably also acid calcium
citrate) resulting from the action of acid furnished
by the fermentation of milk-sugar, perform several
functions in the cheese-making process.

( I ) These soluble calcium salts favor the rapid-
ity and completeness of the action of rennet-extract
in coagulating milk ; in fact, their presence in cer-
tain amounts is essential to the action of the ren-
net-enzym. Now, while the immediate object of
ripening milk in cheese-making is to convert milk-
sugar into lactic acid, the real purpose is the forma-
tion of soluble calcium salts to hasten rennet
coagulation.

FUNCTIONS OF MILK CONSTITUENTS lj$3

(2) The soluble calcium salts probably perform
some work in assisting in the contraction of the
curd. After the curd is formed in the cheese-vat,
the milk-sugar remains in the coagulated mass at
first, but gradually passes out in solution as the
whey exudes from the pieces of curd. The amount
of sugar remaining in the curd is much reduced,
but the formation of lactic acid continues, thus in-
creasing the amount of calcium lactate, acid calcium
phosphate, acid calcium citrate, etc. Cheese-makers
speak of acid in curd frequently when they really mean
whey or, more strictly, milk-sugar contained in whey
within the pieces of curd and ready to form lactic acid
sooner or later.

(3) The formation of soluble calcium salts is
probably also more or less intimately connected
with the changes in the curd during the cheddaring
process, when the grain or texture rapidly changes,
finally resembling the fiber of the cooked meat on
a chicken's breast and when the curd develops the
characteristic plastic properties exhibited by form-
ing long, silky strings, when brought into contact
with a hot iron. This change appears to depend upon
the conversion of paracasein into a substance soluble
in brine solution (p. 147).

The conversion of milk-sugar into lactic acid,
with consequent formation of increasing quantities
of soluble calcium salts, continues quite rapidly
throughout the cheese-making process and also in
the press and still later in the cheese. Under ordi-
nary conditions, the last trace of milk-sugar disap-
pears in about two weeks after the cheese is made.
But, throughout the process of cheese-making, when

l84 SCIENCE AND PRACTICE OF CHEESE-MAKING

the conditions are normal, there is never enough sugar
converted into lactic acid to combine with all the avail-
able calcium in cheese and form free lactic acid; and
there is never left in the cheese, under normal con-
ditions, enough milk-sugar to form free acid. There-
fore, in normal cheddar cheese, we never have free
lactic acid.

When a large amount of whey is left in cheese,
that means a corresponding amount of milk-sugar,
a correspondingly large amount of acid, with forma-
tion of increased amounts of calcium salts, resulting
in the production of what is known as "acid" or ''sour"
cheese.

(4) Another well-recognized function of milk-
sugar, as a result of the formation of lactic acid and
acid salts in milk, is the prevention of the growth
of other micro-organisms which are often present
in milk and give rise to forms of fermentation that
interfere seriously with the production of good
cheese, such as the micro-organisms that produce
gases, ill-smelling compounds, etc. It is known that,
if the acid salts and milk-sugar in cheese-curd are
removed, as is done in the case of the "soaked-
curd" process (p. 57), the resulting cheese undergoes
abnormal changes in ripening, forming products that
are putrefactive in character and which seriously im-
pair or destroy the value of the cheese as food.

(5) It may be found that the fermentation products
of milk-sugar are more intimately associated with the
development of cheese flavor than has been previously
thought.

SALTS OF MILK
The salts of milk appear, as already explained in
connection with the functions of milk-sugar, to

FUNCTIONS OF MILK CONSTITUENTS 185

depend largely for the active part which they take
in cheese-making upon the presence of lactic acid,
bv which insoluble calcium salts are converted into
soluble forms, especially soluble calcium phosphate.
When we determine the acidity of whey at various
stages of the operations of cheese-making, we are
really measuring directly the formation of acid com-
pounds, which furnish, of course, a measure of the
amount of lactic acid that has been formed.

It has been noticed that, when in the making of
cheese a higher degree of acidity is produced, while
the curd is still in the whey, that the amount of ash
in the cheese is less than when so much acid is nov
formed. This is in accordance with what one would
expect, since the more rapidly the insoluble calcium
baits are dissolved while the curd is in the cheese-vat,
the larger is the amount of soluble salts going into
ilie whey.

CHAPTER XVII

Milk Constituents and Yield of Cheese

The relation of the composition of milk to yield
of cheese is a subject of the highest practical in-
terest and importance to cheese-makers. Compara-
tively little was known about it previous to 1892,
because attention had been completely absorbed by
the merely mechanical methods of cheese-making.
We were completely in the dark in regard to such
fundamental facts as the relation of fat and casein
in milk to yield of cheese, the character and extent
of losses of milk constituents in cheese-making,
their causes and remedies, and, in general, the de-
tailed relations existing between cheese and the
material from which it is made. So profound was
the ignorance regarding milk constituents and their
relation to yield of cheese that it was very gener-
ally believed that the same amount of cheese was
made from 100 pounds of milk in the case of the
milks of different herds. We now have on hand an
immense mass of data, the accumulated results of
the investigation work of our American experiment
stations, and these data enable us to reach ver}^
definite, positive and final conclusions.

The amount of fresh or green cheese produced by
100 pounds of milk depends upon three factors :

i (i) The percentage of fat and of casein in milk.
/ (2) The percentage of fat and of casein lost in
cheese-making.

186

MILK AND YIELD OF CHEESE 187

y (3) The amount of whey retained in cheese.

THE RELATION OF FAT AND OF CASEIN
TO YIELD OF CHEESE

Those constituents of the milk that are insoluble
and are present in suspension as solids or in emul-
sion, those that can be, for the most part, mechan-
ically held by the coagulated casein, furnish the
solid materials for cheese. They are: (i) Milk-
fat; (2) milk-casein; and (3) insoluble phosphates.
The fat and casein constitute so large a proportion
of these cheese-producing solids of milk that we
should not be far from the truth in saying that
only these two constituents of normal milk are
prominent in determining the yield of cheese. These
two constituents of milk form over QO per cent of
the solid portion of cheese (cheese-solids) ; the only
other solids in cheese are comparatively small in
amount, consisting essentially (i) of the calcium
sajis of phosphoric, lactic .and citric acids : . (2) of the
salt added in cheese-making; (3) of a small amount
of milk-albumin; and (4) of some milk-sugar, which
mostly disappears in a few days.

The yield of cheese from milk varies as the
amount of fat and casein in m.ilk vary, provided the
conditions of cheese-making are the same, includ-
ing under these conditions the quality of the milk
with reference to cleanliness (bacterial content), (p.
4). As a rule, when the percentage of fat in milk
increases, the percentage of casein also increases (p.
169) and the yield of cheese increases in proportion
to the increase of fat and casein. At this point, the

l88 SCIENCE AND PRACTICE OF CHEESE-MAKING

questions naturally arise: How much does milk-fat
contribute to cheese yield? How much does milk-
casein contribute to cheese yield ? This at once
brings us to a consideration of the losses of these
constituents in the process of cheese-making.

THE LOSSES OF MILK CONSTITUENTS IN

CHEESE-MAKING

In transferring fat and casein from milk into
cheese through the operations of cheese-making,
certain amounts of these constituents are unavoid-
ably lost in the escaping whey and- do not, conse-
cjuently, contribute to the yield of cheese. It is
obvious, therefore, that the cheese yield from a
given amount of milk is dependent, to some extent,
upon the degree of completeness with which the
fat and casein of milk are worked into cheese; that
is, upon the degree of success experienced in re-
ducing these losses to a minimum. It is very im-
portant, then, that in studying the relation of milk
constituents to yield of cheese, we learn something
of the extent to which such losses are found in actual
experience, the conditions responsible for these losses,
and the means by which they can be made as small
as possible.

The losses of milk-fat in cheese-making. — Less
than 20 years ago cheese-makers almost universally
believed that all fat in milk above 3.5 or 4.0 per
cent must go into whey and not into cheese. Breed-
ers of cows giving milk low in fat content openly
declared, and without contradiction, that only cows
of this type could be suitable for profitable cheese-
making, because it was impossible to transfer the
extra milk-fat into cheese when milk contained over

MILK AND YIELD OF CHEESE 189

3.5 per cent. This question has been studied ex-
haustively at the New York experiment station
under a great variety of conditions, including extended
investigations in case of actual operations in many
different cheese-factories. The following institu-
tions have contributed additional, though less exten-
sive, data, which fully confirm the results obtained
in New York: The experiment stations of Wiscon-
sin, Minnesota, Iowa, Vermont, Utah and the Ontario
agricultural college. Probably much unpublished work
has been done elsewhere.

Taking the results of extended study under
cheese-factory conditions, we have found that the
amount of fat lost for lOO pounds of milk varies
from 0.20 to 0.50 pound (equivalent to 0.22 to 0.55
per cent of fat in whey), the average being 0.33
pound (equivalent to 0.36 per cent of fat in whey).
This amounts to about 9 per cent of the fat in the
milk. In one factory which was under observation
for an entire season, the loss of fat for 100 pounds
of milk varied from 0.20 to 0.36, and averaged 0.25,
pound (equivalent to 0.22, 0.40 and 0.27 per cent
of fat in whey). This average is equivalent to 7
per cent of the fat in the milk. In another factory,
which was under observation at the same time,
the amount of fat lost varied from 0.26 to 0.50,
and averaged 0.37, pound (equivalent to 0.29, 0.55
and 0.42 per cent of fat in whey). The average
loss in this case is nearly 10 per cent of the fat in
the milk. In some cases, losses of fat under 0.20
pound have been reported, but such experience is
not common in most cheese-factories. In general,
it may be said that really efficient work is not

190 SCIENCE AND PRACTICE OF CHEESE-MAKING

being done by a cheese-maker when the percentage
of fat in whey exceeds 0.30, if the milk furnished
is in good condition in respect to cleanHness. An
average loss of 0.25 pound (4 ounces) of fat for loci
pounds of milk indicates excellent work under factory
conditions ; this means that about 93 per cent of the
fat in milk is recovered in cheese and not over 7 per
cent lost in whey.

The data embodied in the following table include
the results of several seasons' work in cheese-fac-
tories :

AMOUNT OF FAT IN WHEY AT CHEESE-FACTORIES DUR-
ING SEASON

Month

Average
per cent of
fat in milk

Pounds of fat lost in whey from
100 pounds of milk

April

May

June

July

August . . . .
September
October. . .

3.43
3.58
3.64
3.62
3.84
3.98
4.23

Lowest
0.29
0.20
0.20
0.21
0.22
0.22
0.26

Highest
0.42
0.50
0.36
0.45
0.40
0.46
0.44

Average
0.36
0.35
0.28
0.32
0.34
0.37
0.33

The tabulated results on the next page show the
relative amounts of fat lost in normal milks containing
different percentages of fat. These results are in
harmony with those of other investigators and the
facts all go to show that the loss of fat in cheese-
making is quite independent of the amount of fat in
milk. The variations that occur in loss of fat are
due either to the defective condition of the milk with
reference to bacterial content, or to some special fault
in the details of methods employed in cheese-making,
or to both causes.

MILK AND YIELD OF CHEESE

191

Even when cream is added to normal milk to an
extent sufficient to raise the fat content to 7 or 8
per cent, the increased loss of fat, though consider-
able, is not necessarily greater in proportion to the
increase of fat in milk.

AMOUNT OF FAT LOST IN CHEESE-MAKING IN CASE OF

NORMAL MILKS

Group

Number
of ex-
peri-
ments

Per cent

of fat

in milk

Pounds of fat lost in whey
for 100 pounds of milk

Percent-
age of fat
in milk
lost in
whey

Percent-
age of fat

in milk
retained
in cheese

II
III
IV
V

Lowest

Highest

Average

3.0-3.5

0.21

0.39

0.32

9.55

112

3.5-4.0

0.21

0.50

0.33

8.33

4.0-4.5

0.20

0.46

0.32

7.70

4.5-5.0

0.17

0.49

0.28

5.90

5.0-5.25

0.27

0.35

0.31

6.00

90.45
91.67
92.30
94.10
94.00

Why it is impossible to prevent loss of fat in
cheese-making. — Attention has already been called (p.
140) to the fact that fat is present in milk in the
form of very small globules, one cubic centimeter
of ordinary milk containing between one and two
billion globules. When the rennet-extract causes
the casein throughout the mass of milk to solidify
or coagulate, the fat-globules are retained or im-
prisoned in the solidified mass just where they
are at the instant of coagulation. When the curd-
knife passes through the solid mass, immense num-
bers of the fat-globules are exposed on every cut
surface and billions of these are disengaged from
the free surfaces of the small pieces of curd during
its manipulation. The fat-globules, thus detached

192 SCIENCE AND PRACTICE OF CHEESE-MAKING

from the hold of the curd, float free in the whey and
are consequently lost to the cheese.

Conditions favoring loss of fat in cheese-making.

—Among the numerous conditions contributing to
an increased loss of fat in cheese-making are the fol-
lowing :

(i) Any condition which interferes with com-
plete coagulation of casein by rennet-extract, such
as dilution with water, presence of preservatives,
as salt, formalin, etc., necessarily causes extra loss of
fat.

(2) There may occur cases of abnormal compo-
sition of milk, in which the casein is abnormally
low in relation to fat. Attention has already (p.
164) been called to this condition as likely to occur
in times of drouth. Cheese-makers do not realize
the abnormal nature of the milk and so do not ob-
serve the precautions necessary in handling milk
that is abnormally high in fat in relation to casein.
But another condition usually prevails at such times,
which makes the losses of fat unavoidable, and that is
the presence of bacterial ferments, resulting from the
accompanying effects of drouth such as contaminated
water supply.

(3) Failure to keep the fat well distributed
through the milk before and after adding rennet
results in some accumulation of fat at the surface
of the milk, most of which goes into the whey.

(4) In case of milk containing particles of dried
cream or churned fat-granules, there is usually in-
creased loss of fat, unless the particles are completely
worked back into the form of emulsion by sufficient,
but not rapid, warming and careful stirring.

MILK AND YIELD OF CHEESE I93

(5) When milk is run through a separator and
the cream and skim-milk then remixed, increased
loss of fat occurs when such milk is made into
cheese.

(6) Tarring or stirring milk after rennet coagu-
lation has commenced and before it is completed may
cause serious loss of fat.

(7) When curd is cut in too soft a condition, the
loss of fat is greater.

(8) Added losses of fat in whey are caused by
dull knives or by violent, careless and rapid motions
of knife in cutting curd.

(9) Extra losses of fat occur when the curd in the
soft stage is roughly or carelessly handled.

(10) Another cause of increased loss of fat in
whey is heating the curd too rapidly or to too high a
temperature.

(11) If the curd is not well firmed at the time
the whey is removed, vigorous hand stirring causes
large loss of fat.

(12) Excessive piling of curd, previous to ched-
daring, causes unnecessary loss of fat.

(13) Tf the curd is salted at a temperature above
90° F., fat is apt to exude along with the whey and
be lost.

(14) If curd is put in press too warm, the amount
of fat lost in pressing increases on account of the
greater softness of the warm curd.

(15) Too rapid application of pressure in the
cheese-press increases loss of fat.

(16) Fermentations producing large amounts of
gas and resulting in "floating" curds, also curd-
dissolving fermentations, are attended with extra

194 SCIENCE AND PRACTICE OF CHEESE-MAKING

losses of fat. The conditions of cheese-making have
to be varied under such circumstances so as to make
the best of a bad matter and obtain as good a product
as possible in respect to texture, body and flavor.
Such variations from the usual conditions of cheese-
making cause extra losses of fat (p. 124).

(17) The making of cheese from milk containing
too much acid results in unusual losses of fat, if the
conditions are varied so as to obtain the best product
possible from such milk (p. 122).

(18) Milling at too high a temperature, or too
rapidly, or with dull knives, or feeding to mill too
fast, or allowing the curd to become matted after
milling, — any of these conditions increases loss oE
fat.

The losses of casein in cheese-making. — The
larger portion of the casein lost in cheese-makin;^
appears to be in the form of fine particles of the
coagulated casein (paracasein), which pass througU
the strainer when the whey is removed from th i
curd. These fine particles can readily be seen by
letting a pail of freshly drawn whey stand until the
curd particles settle. If the whey is then carefully
poured from the pail, a noticeable quantity of finely
divided curd can be seen at the bottom of the pail.
This loss does not appear to be entirely avoidable,
but is needlessly made greater ( i ) by carelessness
or violence in cutting curd and in subsequent han-
dling when the curd is still soft; (2) by agitation
while removing the whey from the curd; (3) by
imperfect strainers; and (4) by any condition that
interferes with the complete coagulation of the
milk-casein by rennet (p. 24). The amount of

MILK AND YIELD OF CHEESE

195

casein that thus passes into the whey averages about
o.io pound for 100 pounds of milk.

In some cases of badly contaminated milk, casein-
dissolving ferments may cause more or less loss of
casein.

FIG. 34 — COMPOSITION OF MILK, SHOWING PROPORTIONS OF
WATER AND DIFFERENT SOLIDS. THE NUMBERS REP-
RESENT POUNDS IN 100 POUNDS OF MILK

COMPOSITION OF WHEY

The composition of whey (Fig. 35) varies ac-
cording to (i) the composition of the milk from
which it comes, and (2) the losses of milk constit-
uents due to conditions attending the operations
of cheese-making. It is obvious that the larger the
percentage of sugar, albumin and soluble salts in

196 SCIENCE AND PRACTICE OF CHEESE-MAKING

milk, the larger will be their amount in whey. The
matter of losses of fat and casein we have already
treated. The amount of acid in whey varies
greatly, depending largely on the time when the
determination of acidity is made. When the whey
is removed from the curd, the acidity (equivalent

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FIG. 35 — DISTRIBUTION OF MILK CONSTITUENTS IN

CHEESE AND WHEY

From 100 pounds of milk, we obtain '10.6 pounds of cheese and 89.4 pounds of
whey. The cheese contains 3.9 pounds of water, 3.7 fat, 2.4 casein, 0.4^ salts and
albumin and 0.2 sugar. The whey contains 83.1 pounds of water, 5.25 sugar and
salts, 0.28 fat, 0.10 casein and 0.67 albumin. The lower part of the diagram shows
amount and composition of cheese. The remainder is whey (water and whey-
solids.)

to lactic ax:id) varies from 0.16 to 0.18 per cent, and
this amount increases to the end of the cheese-
making process. The whey, when it first separates
from the curd, shows less acidity than the milk
from which it comes, because the whey does not

MILK AND YIELD OF CHEESE

197

contain the milk-casein, which, as we have seen
(p. 145), has the power of neutraHzing considerable
alkali, and of acting in this way like an acid. The
percentage of sugar in whey depends upon the time
when the whey is tested, the sugar decreasing in
amount as it is changed into lactic acid.

In closing this discussion of the losses of milk
constituents in cheese-making, we give below tab-
ulated results of work showing the composition of
whey as obtained at cheese-factories in New York
through the work of the New York experiment
station.

COMPOSITION OF CHEESE-FACTORY WHEY

Month

Per cent
of water

Per cent
of solids

Per cent

of fat

Per cent

of proteins

(chiefly

albumin)

Per cent
of sugar,
salts, etc.

April

93.17
92.98
92.99
93.05
93.08
93.18
93.04

6.83
7.02
7.01
6.95
6.92
6.82
6.96

0.40
0.38
0.31
0.35
0.38
0.41
0.38

0.73
0.81
0.88
0.83
0.80
0.85
0.98

5.70

May

5.83

June

5.82

July

5.77

August

September

October

5.74
5.56
5.60

Average

93.04

6.96

0.36

0.84

5.76

The following figures show the extreme variations
in the constituents of whey during the period of

mvestigation :

Solids

Fat

Proteins

Sugar, salts, etc.

Lowest
per cent

Highest
per cent

6.43

7.52

0.22

0.55

0.65

1.07

5.39

6.43

198 SCIENCE AND PRACTICE OF CHEESE-MAKING

THE RELATION OF WATER TO YIELD OF

CHEESE

As we have seen, the amount of soHds in cheese
is determined by the amount of fat and casein in
milk when the conditions of manufacture are nor-
mal. When we come to consider the amount of
water held in cheese, we find that it bears no rela-
tion whatever to the amount of water in milk, but
that it is dependent upon the conditions present in
the operations of cheese-making, such as the degree
of fineness or coarseness in cutting curd, temper-
ature used in heating curd, degree of acidity,
amount of salt, etc. (p. 45). The amount of water
in cheese can easily be made to vary 10 per cent.
Fresh cheese contains an average of 37 per cent of
water, but in actual factory work the variations may
be very wide, especially where cheese is manufac-
tured for export trade at one part of the season and
for home trade at another. Therefore, when we are
discussing yields of cheese from milk, and especially
in the case of comparison of dififerent milks, it is
absolutely necessary to know the percentage of
water in the cheese. When we compare yields
of cheese from different milks or under different con-
ditions of manufacture, we should base our com-
parison on the yield of cheese which contains a
uniform percentage of moisture, if the results are
to have any definite relation to the milk con-
stituents.

So important is it for us to appreciate the extent
of variation of water in cheese, as made at cheese-
factories, that we will present data obtained by the
New York experiment station in 200 experiments

MILK AND YIELD OF CHEESE

199

carried on at cheese-factories under the usual con-
ditions. In the table below, we present the results
in groups, based on the percentage of fat in milk;
in each group we give ( i ) the extreme variations in
yield of cheese; (2) the percentage of moisture
in the cheese; and (3) the corresponding yield of
cheese based on a content of 2^y per cent of water.

YIELD OF CPIEESE AS AFFECTED BY MOISTURE

Number
of experi-
ments

Per cent

of fat

in milk

Pounds of cheese

made for 100

pounds of mUk

Per cent
of water
in cheese

Pounds of cheese

(containing 37 pel

cent of water)

made for 100

pounds of milk

3.00-3.49

3.50-3.74

3.75-3.99

4.00-4.19

4.20-4.40

Lowest -
Highest-
Lowest -
Highest-
Lowest -
Highest-
Lowest -
Highest-
Lowest -
Highest-

8.47 (

34.77

9.68

39.09

9.25 1

33.75

10.42 1

40.47

9.60 1

^32.69

11.00

1 40.17

10.24 J

[34.15

12.44

1 42.90

10.64 J

'33.53

13.17 1

[43.89

8.43

9.46

9.32

10.60

9.76

10.76

10.38

10.93

11.03

12.03

In studying these results, we see that in the case
of each group the cheese yield varies widely, as
shown in the third column of the table; and also
that the percentage of water varies widely, as
shown in the fourth column. To illustrate, we
will take the group representing milk containing
4 to 4.19 per cent of fat. The factory yield of
cheese in this group varies from 10.24 to 12.44
pounds, a difference of 2 pounds, while the water
in 100 pounds of cheese varies from 34.15 to 42.90
pounds. In the last column we see what the nor-
mal variation should be in the yield of cheese

20O SCIENCE AND PRACTICE OF CHEESE-MAKING

having the same percentage (37) of water; it goes
from 10.38 to 10.93, 3. variation of 0.55 pound, as
against an actual variation of 2 pounds. This
difference, 1.45 pounds, is wholly due to differ-
ence of water in cheese. In the last group of
the table, the factory yield of cheese varies 2.53
pounds, while the normal variation would be only
l.o pound. We see at the same time that the amount
of water in 100 pounds of cheese varies over 10
pounds.

These results might appear to indicate that
cheese-makers have no control over the amount of
water in cheese, but such a conclusion would not
be justified, because it is well known that a skill-
ful cheese-maker, under normal conditions, can
control the amount of water in cheese within 3
or 4 per cent, so that the normal range of varia-
tion is usually between 35 and 38 per cent. The large
amounts of water in the cases noted in the preceding
table appeared there, not because the cheese-makers
had no control of the process, but for the very opposite
reason, that they did have such control and deliber-
ately made the cheese to hold a high percentage O-^
water

THE COMPARATIVE VALUE OF DIFFER-
ENT MILKS IN RELATION TO
CHEESE-PRODUCING SOLIDS

From what has preceded, it can be readily un-
derstood that we can divide the constituents of milk
into two general classes, when considered with ref-
erence to their relations to cheese. The casein, fat

MILK AND YIELD OF CHEESE 201

and insoluble salts constitute one group, furnishing
most of the solid matter in cheese, and we can call
these constituents cheese-producing solids. On an
average, milk contains about 0.90 per cent of salts,
of which about 0.25 pound goes into cheese for each
100 pounds of milk and 0.65 pound into whey, vary-
ing, of course, with many conditions. The other
constituents of the milk-solids, the sugar, the albu-
min and the soluble salts, those constituents of the
milk that exist in true solution, pass largely into
the whey and are lost, except in so far as they are
held by the water or whey in the cheese. Their
amount in cheese will depend upon the amount of
whey retained in the cheese. Those solid constitu-
ents existing in solution in the whey we may prop-
erly characterize as whey-solids. This division of milk
constituents into cheese-producing solids and whey-
solids is, of course, not strictly accurate, because
small amounts of cheese-solids pass into whey and
small amounts of whey-solids are retained in
cheese. But, for the purpose of studying the gen-
eral relations of milk-solids to cheese, the classifi-
cation is close enough. The figures presented be-
low are largely taken from work done at the New
York experiment station, covering a period of four
years and are largely derived from actual cheese-
factory conditions.

The cheese-producing solids were found to aver-
age 6.50 pounds, varying in extreme cases from
5.25 to 7.75 pounds for 100 pounds of milk, but the
greater portion of factory milk comes within the
narrower limits of 5.75 to 7.25 pounds. The whey-
solids of milk varied from 5.75 to 6.75 pounds and

202 SCIENCE AND PRACTICE OF CHEESE-MAKING

averaged 6.25 pounds. Stated in another form, 49
per cent of the milk-soHds goes into whey and 51 per
cent into cheese as an average of factory milk.

The following arrangement shows the extent of
average monthly variation during the factory
season :

CHEESE-PRODUCING SOLIDS AND WHEY SOLIDS IN

CHEESE-FACTORY MILK

Month

Percentage of cheese-
producing solids in milk

Percentage of whey-
solids in milk

Lowest

Highest

Average

Lowest

Highest

Average

April

May

June

July

August

September.. .
October

5.75
5.68
6.06
6.01
6.09
6.27
7.02

6.14
6.91
6.61
6.60
6.76
7.14
7.69

5.97
6.17
6.36
6.30
6.48
6.78
7.29

5.94
6.11
6.17
6.10
6.06
5.86
5.96

6.09
7.78
6.44
6.47
6.35
6.26
6.44

6.01
6.26
6.28
6.22
6.17
6.08
6.21

Expressing the relations of the general averages
in the preceding table in the form of percentages of
milk-solids, we have the following table:

Month

Pounds of milk-
solids in 100
pounds of milk

Percentage of total
solids of milk in
form of cheese-
producing solids

Percentage of total
solids in milk in
form of whey-
.solids

April

Jlay

June

July

August

September .
October. . . .

11.98
12.43
12.64
12.52
12.65
12.86
13.50

49.8
49.6
50.3
50.3
51.2
52.7
54.0

50.2
50.4
49.7
49.7
48.8
47.3
46.0

We see a general tendency for the cheese-producing
solids in milk to increase during the factory season,

MILK AND YIELD OF CHEESE

203

which is only another way of saying that the per-
centag-e of fat and of casein increases with advance
of lactation, (p. 166).

Before leaving this phase of the subject, it will
be found interesting to compare the ratio of cheese-
producing solids and whey-solids in milk varying
considerably in percentage of fat. From the figures
in the following table, it is very strikingly shown
that in normal milk rich in fat a very much larger
proportion of the milk-solids goes into cheese and
correspondingly less into whey, than in the case of
milk poorer in fat.

CHEESE-PRODUCIXG SOLIDS AND WHEY SOLIDS IN

RICH AND POOR MILK

Per cent

Per cent' of

Per cent of

Per cent

of cheese-

of whey

solids in form

of solids

of fat

producing

solids

of cheese-

of whey-

solids

11.80

3.26

5.71

6.09

48.4

51.6

12.65

3.76

6.89

5.76

54.5

45.5

12.75

4.01

6.47

6.28

50.7

49.3

14.30

4.28

7.32

6.98

51.1

48.9

14.50

4.89

8.24

6.26

56.9

43.1

14.90

5.38

8.54

6.36

57.3

42.7

15.40

5.78

9.06

6.34

58.8

41.2

DISTRIBUTION OF MILK CONSTITUENTS
IN WHEY AND CHEESE

Having learned what the principal losses of
cheese-producing solids are, we will next show by
illustrations in what amounts the different constit-
uents of milk are divided between whey and
cheese in cheese-making. The following results
are based on average losses of milk constituents..

204 SCIENCE AND PRACTICE OF CHEESE-MAKING

The cheese is assumed to contain 2)7 P^^ cent of
water, about 5 per cent of salts and no allowance
is made for mechanical losses other than as indi-
cated

Water

Milk-
solids

Fat

Casein

Albumin

Sugar,
ash, etc.

Milk...
Whey..
Cheese

Pounds

100.00

91.70

8.30

Pounds
88.60

85.55
3.05

Pounds

11.40

6.15

5.25

Pounds
3.00
0.21
2.79

Pounds
2.10
0.10
2.00

Pounds
0.60
0.57
0.03

Pounds
5.70
5.27
0.43

II.

Milk...

100.00

Whey..

89.40

Cheese

10.60

87.00

83.10

3.90

13.00
6.30
6.70i

4.00
0.28
3.72

2.50'

0.10

2.40

0.70
0.67
0.03

5.80
5.25
0.55

III.

Milk...

100.00

85.50

14.50

5.00

2.90

Whey..

87.10

80.75

6.35

0.35

0.10

Cheese

12.90

4.75

8.15

4.65

2.80

0.75
0.72
0.03

S.85
5.18
0.67

In connection with this table, study Figs. 34, 35
and 2i^.

RELATION OF MILK-FAT TO CHEESE

YIELD

Much study has been given, especially in New
York, to the quantitative relations existing between
the percentage of fat in milk and the yield of cheese,
or the amount of cheese corresponding to one pound
of fat in milk. The relation is a very simple one to
calculate and is found by dividing the number of
pounds of cheese made from 100 pounds of milk by
the number representing the per cent of fat in milk.
For example, the yield of cheese from 100 pounds
of milk containing 3 per cent of fat is 8.31 pounds;

MILK AND YIELD OF CHEESE 205

the ratio of milk-fat to cheese yield is, therefore,
8.31-^3, which equals ^.yy, that is, in this case, one
pound of fat in milk is equivalent to 2..^^ pounds of
cheese. In the case of milk containing 4 per cent of
fat and producing 10.60 pounds of cheese for 100
pounds of milk, each pound of fat in milk is equiva-
lent to 2.65 pounds of cheese.

The study of this relation was first undertaken at
the New York experiment station to ascertain
whether a pound of fat in all normal milks is
equivalent to the same amount of cheese. The
bearing of this point upon the use of fat in milk as
a basis of paying for milk at cheese-factories is
obvious. If a pound of fat in milk were always
equivalent to the same amount of cheese, then no
question could arise as to the strict accuracy of a
milk-fat basis in making dividends. If the amount
of cheese made for a pound of fat in milk varies,
then the fat could not be regarded as a strictly ac-
curate measure of cheese yield, and other points than
yield would need to be considered, such as the quality
of the cheese, in measuring the value of milk for
cheese-making. The details of the subject of methods
of paying for milk at cheese-factories will be con-
sidered later (p. 253).

We have already seen that the yield of cheese
is chiefly dependent upon two constituents of milk,
casein as well as fat. It is obvious that if fat and
casein were always present in milk in the same
relative proportions, then the yield of cheese would
always be in the same uniform ratio to milk-fat.
But we have found (p. 164) that the ratio of fat
and casein in milk varies considerably and, for

206 SCIENCE AND PRACTICE OF CHEESE-MAKING

this reason, the ratio of milk-fat to yield of cliees(*
must also vary. It is a matter of practical interest
and importance to know what the extent of such
variations may be.

6. 00
IS. 20

FIG. 36 — YIELD AND CONSTITUENTS OF CHEESE FROM 100

POUNDS OF MILK CONTAINING AMOUNTS OF FAT

VARYING FROM 0.10 PER CENT (SEPARATOR SKIM-

MILK) up to 6.00 PER CENT.

The figures immediatelv above each column trive the numher of pounds of
cheese (containing 37 i)er cent of water) marte from 100 pounds of millt. The
figures within the diagram give the i)Ounds of each constituent in the cheese,
The figures at the extreme top of the diagram indicate percentages of fat in
milk.

Taking- milk as it averages, we find the following
variation of relation between fat and cheese yield in
normal milks containing different amounts of fat.
The cheese yield is based on a uniform percentage
of water in the cheese, 2)7 per cent.

MILK AND YIELD OF CHEESE

207

RATIO OF FAT TO CHEESE YIELD IN NORMAL MILK

Pounds of cheese

Per cent of

Pounds of cheese

made for each

fit in milk

casein in milk

made from 100
pounds of milk

pound of fat
in milk

3.00

2.10

8.30

2.77

3 25

2.20

8.88

2.73

3. SO

2.30

9.45

2.70

3.75

2.40

10.03

2.67

4.00

2.50

10.60

2.65

4.25

2.60

11.17

2.63

4.50

2.70

11.74

2.61

4.75

2.80

12.31

2.59

5.00

2.90

12.90

2.58

In our study of the ratio of fat and casein in
milk (p. 164), it was seen that the casein does not
increase as rapidly as fat does, and that, therefore,
milk richer in fat usually contains less casein in
proportion to fat than does milk less rich in fat.
In harmony with this condition, and as a result of
it, the amount of cheese made for a pound of milk-
fat decreases as the percentage of fat in milk
increases. This is clearly shown in the preceding
table.

An interesting fact shown in this table is that
the rate of decrease of the ratio of fat to cheese
yield is less rapid as the percentage of fat in milk
increases. Thus, in the case of milks containing
3 and 3.25 per cent of fat, the decrease of cheese
yield in relation to fat is from 2.77 to 2.73, a differ-
ence of 0.04 pound ; between 3.25 and 3.50, and also
between 3.50 and 3.75, the decrease is 0.03; for
each 0.25 per cent of increase of milk-fat from
3.75 to 4.75 per cent, the decrease in the ratio is
only 0.02; and between 4.75 and 5.00 per cent,
the decrease is only o.oi. This is explained by the

208 SCIENCE AND PRACTICE OE CHEESE-MAKING

fact, already emphasized (p. 190), that in the case
of milk rich in fat, a smaller proportion of the fat
is lost in cheese-making- than in the case of milk
poorer in fat.

PER CENT. OF FAT IN MILK AND YIELD OF CHEESE

FIG. 37 — DIAGRAM SHOWING YIELD AND CONSTITUENTS OF

CHEESE FROM 100 POUNDS OF MILK OF DIFFERENT BREEDS

OF DAIRY cows

The figures inimediately above each cohinin give the number of pounds
of cheese (containing 37 per cent of water) made from 100 pounds of milk. The
figures in the diagram give the pounds of each constituent in tlie cheese. The
figures at the top of the diagram indicate percentage of fat in milk.

In this connection, it will be interesting to observe
how the matter works out when applied in the case
of the milk of different breeds of cows.

MILK AND YIELD OF CHEESE

209

RATIO OF FAT TO CHEESE YIELD IN MILK OF DIFFERENT

BREEDS

Breed

Per cent

of fat

in milk

Per cent

of casein

in milk

Pounds of

cheese made

for 100

pounds

of milk

Pounds of
cheese made

for each

pound of fat

in milk

Holstein-Friesian. . . .

Ayrshire

American Holdemess

Shorthorn

Devon

Guernsey

Jersey

3.26
3.76
4.01
4.28
4.89
5.38
5.78

2.20
2.46
2.63
2.79
3.10
2.91
3.03

8.90

10.14
10.82
11.52
13.02
13.51
14.36

2.73
2.70
2.70
2.70
2.66
2.51
2.49

Before closing our discussion of this subject, we
wish , to call attention to the fallacy that may be
introduced by wide variations in the water content
of cheese, when we are making a comparison of the
yield of cheese with reference to the milk-fat. For
example, 100 pounds of milk containing 4 per cent
of fat may be made into cheese with a yield of 10.40
pounds in one case, and 11.00 pounds in another,
the difference being due wholly to water. In one
case the yield is 2.60 pounds for one pound of milk-
fat; in the other, it is 2.75 pounds. It is thus seen
that, when such comparisons are to be made with
reference to the relation of fat to yield of cheese,
the cheese should contain the same percentage of
water. The table on page 199 well illustrates the
variations of yield in relation to water. If we use
the results there given as a basis for calculating
the yield of cheese in relation to milk-fat, we find
that the amount of cheese made for one pound of
milk- fat varies from 2,51 to 3.1 1, when we take the
factory yield, with its great variation of water; but.

2IO SCIENCE AND PRACTICE OF CHEESE-MAKING

if the calculation is based on cheese containing a fixed
percentage of water, the cheese yield varies in relation
to fat only from 2.61 to 2.89. This is a much nar-
rower range and represents such variations as are
properly due to differences in composition of milk.

CHAPTER XVIII

Methods of Calculating Yield of Cheese

In the chapter preceding, we have seen that fat
and casein in milk furnish most of the soHd mate-
rial which we find in cheese ; we have also seen that
certain amounts of fat and of casein are inevitably-
lost in whey during the operations of cheese-mak-
ing; and we have further seen that the amount of
water in cheese may be made to vary largely or
may be held within comparatively narrow limits,
being controlled by the conditions used in the
process of cheese-making. From our preceding
discussion, it might seem that the relations between
composition of cheese and yield of milk were suf-
ficiently understood to enable us to calculate the
amount of cheese yield when the percentages of fat
and of casein in milk are known, or even when the
fat alone is given. As a matter of fact, several
different methods have been proposed and have
been employed in studying problems of cheese
yield. There is an advantage in having some fairly
reliable method for ascertaining the amount of
cheese that can be made from loo pounds of milk.
Results thus obtained afford a basis of comparison
with actual results. A cheese-maker can, by such
means, ascertain if his losses in cheese-making are
excessive or if he is retaining too much or too little

water in cheese.

311

212 SCIENCE AND PRACTICE OF CHEESE-MAKING

The different methods of calculating cheese yield
which have been in use have never been carefully
compared in such a way as to show their relative
accuracy or value. It has seemed desirable that such
a study should be made, and it is now our purpose
to take up for consideration the various methods
referred to. We shall discuss, in the case of each
method, their underlying principles, indicate the
points of fundamental weakness, and give the results
of an exhaustive comparative study, based upon an
application of each method to 200 experiments in
cheese-making, using for this purpose the work done
at the New York experiment station, which appears
to offer the only material sufficiently complete to be
available for such an investigation.

The methods which have been proposed for use
in calculating the amount of green cheese are the
following :

(i) The use of the percentage of fat in milk,
which, expressed as a formula, is:
Yield of cheese=2.7 Fat.

(2) The use of the percentage of fat in milk and,
in addition, a constant factor. This, expressed as a
formula, is :

Yield of cheese^=i.i Fat+S-Q.

(3) The use of the percentage of fat and of
casein, which can be expressed in the following
form :

Yield of cheese=i.i Fat-}-2.5 Casein.

(4) The use of the percentage of fat in milk and
of the solids-not-fat. This is somewhat more com-
plicated and is expressed thus :

ir- 1 J r 1 / Solids-not-fat -. „^ -,> .\ ^ -«
Yield of cheese— I -I- 0.91 Fat 1 X 1.58

CALCULATING YIELD OF CHEESE 21 3

(5) A new method based on the use of the per-
centage of fat and the percentage of casein (either
actual or calculated). The general formula for this
method is as follows :

y- Id f h _(Fat - 0.07 Fat + Casein - 0.10) X 1.09

1.00 — Water in cheese (expressed as hundredths)

As will be pointed out later, this can be much
simplified, becoming

Yield of cheese=(Fat-|-Casein) Xi-63
in the case of cheese containing a uniform amount of
water {;^y per cent). When only the fat is known and
the casein is calculated from the formula on p. 170
the formula for both casein calculation and calcu-
lation of cheese yield is simplified into one :

(6) Yield of cheese:^2.3 Fat+i4-

These last formulas, based upon results of New
York experiment station work, are now published for
the first time.

Before giving the detailed results of our com-
parative study of these dififerent methods, we will
discuss each one separately, explaining underlying
principles and thus learning how the methods came
to be suggested.

METHOD BASED ON RELATION OF FAT TO
YIELD OF CHEESE (i)

The basis of this method has been discussed in
the chapter preceding. In the investigations carried
on at the New York experiment station, covering
all varieties of factory conditions, it was found that
when the yield of cheese for 100 pounds of milk was
divided by the number representing the percentage
of fat in milk, the. averages, season by season, and

214 SCIENCE AND PRACTICE OF CHEESE-MAKING

factory by factory, were very uniform, being very-
close to 2.72 pounds of cheese for one pound of fat
in milk. The individual results giving the average
varied widely, from 2.51 to 3.1 1. These extreme
variations were due to wide variations in the water
content of the cheese rather than to variation in
the real relation of fat to cheese yield proper, as
we have pointed out in the chapter preceding. Based
on a uniform percentage of water in cheese, the va-
riations would be within much less wide limits,
ranging from 2.61 to 2.89. This variation was due
mainly to variation in the relation of the fat and
casein in the milk and, in some cases, to excessive
losses experienced in the process of cheese-making.
The average result {^.y) is based upon milk con-
taining 3.75 per cent of fat, 2.46 per cent of casein
and upon cheese containing nearly 37 per cent of
water. The ratio of milk-fat to casein is, therefore,
[ 10.665. When the ratio of fat and casein varies
widely from this, we shall get more or less cheese
than that called for by the rule. Thus, in milk in
which the casein is high in relation to fat, as often
happens in milk low in fat, the formula gives too
low results (p. 207) ; while the reverse is true in
case of milk high in fat in relation to casein, as
often happens in milk rich in fat (p. 209). There-
fore, as a result of the variations of the relation of
fat and casein in cheese-factory milks, we may ex-
pect this method to give results varying from the
actual yield of cheese, in extreme and uncommon
cases, to an extent equal to 0.5 to 0.75 pound of
cheese for 100 pounds of milk. When the variation
is greater than this, it is usually due to excessive or
deficient amounts of water in cheese.

CALCULATING YIELD OF CHEESE 215

METHOD BASED ON FAT IN MILK AND A
FIXED NUMBER ADDED (2)

This method, stated in the form of a rule, is as
follows : Multiply the number representing the
per cent of fat in milk by i.i and to the result add
5.9. This formula was worked out at the Wiscon-
sin experiment station and is based upon certain
facts which will be briefly considered. One pound
of milk- fat in butter can readily hold about 0.18
pound of water and it can just as readily hold the
same amount in cheese. We multiply the per cent
of fat in milk by i.i instead of 1.18, because not all
of the milk-fat goes into the cheese. To illustrate,
take milk containing 4 per cent of fat ; in cheese-
making, about 3.72 pounds of this fat in 100 pounds
of milk goes into cheese. This figure, multiplied
by 1. 1 8, equals nearly 4.40, the same as 4 multiplied
by I.I. In other words, the amount of fat that
actually goes into cheese multiplied by 1. 18 gives
about the same result as the amount (per cent) of
fat in milk multiplied by i.i.

The next question that presents itself is as to
why we add the particular number 5.9 to the fat
multiplied by i.i. This figure is based upon the
amount of cheese that can be made from 100 pounds
of separator skim-milk of average composition, and
is supposed to account for the milk-casein, the in-
soluble salts and the moisture not provided foi in
the milk-fat. It is in reality taking account of
casein in milk, but only of the same amount for all
milks.

The inherent weak points of this method are the
following: (i) In the case of excessive losses of.

2l6 SCIENCE AND PRACTICE OF CHEESE-MAKING

fat in cheese-making, the result found by multi-
plying milk-fat by i.i is too high. (2) The estimate
of 5.9 pounds as the measure of the cheese-making
value of casein in skim-milk is based upon skim-
milk of average composition. Therefore, in milk
low in i)crcentage of casein, 5.9 is too high, while
in milk high in casein, the figure is too low. The
method is faulty in that its accuracy depends upon
a uniform percentage of casein in all milks, and we
know that there are quite wide variations.

METHOD BASED ON FAT AND CASEIN IN

MILK (3)

This method of finding the yield of cheese, stated
in the form of a rule, is as follows : Multiply the
number representing the per cent of fat in milk
by I.I, and to this add the result obtained in multi-
plying by 2.5 the number representing the per cent
of casein in milk. This formula was originally
worked out at the Wisconsin experiment station and
was first extensively applied and confirmed by the
work of the New York experiment station.

This method is based upon the following facts :
(i) Milk- fat is capable of holding mechanically
one-tenth of its own weight of water. This has
been already explained in detail in connection with
the discussion of method 2. (2) The reason for mul-
tiplying the amount of casein in milk by 2.5 is
found in the yield of cheese from skim-milk and
air J in the results of some experimental work done
at the New York experiment station. A prepara-
tion of pure casein was made, dried, and then al-
lowed to absorb as much water as it would be

CALCULATING YIELD OF CHEESE 21/

likely to hold in being made Into green cheese. It
was found that one pound of casein takes up water
enough to Increase its weight to 2.25 pounds. If
to this is added the amount of ash constituents
taken up in the same amount of cheese, the weight
is increased to just about 2.5 pounds. This method
has the following defects : ( i ) As already pointed
out, the calculation of the amount of cheese yield
coming from milk-fat is too high when there are
abnormal losses of fat in cheese-making. (2)
When the yield of cheese is calculated by this
method, the percentage of water in cheese is not
uniform, but varies with the percentage of casein
in milk, because the water content of the cheese is
made dependent largely upon the amount of casein.
The Inevitable result is that in case of milks
containing high percentages of casein In relation to
fat, the percentage of water is greater In the cheese
calculated by this method than in case of cheese
from milks in which the amount of casein is lower
in relation to fat. When the ratio of fat and casein
is fairly constant, the results are quite satisfactory.
The manner in which this method of calculation
favors the yield of cheese in case of milk low in fat
and relatively high in casein as against the yield
of cheese in case of milk high in fat and relatively
low In casein can be illustrated by the data in the
table on the next page.

Attention is called to the following facts in
connection with the data contained In this table:
(i) When the cheese made from the two differ-
ent milks contains the same amount of water (37
per cent), the water In the cheese made from 100
pounds of milk amounts to 3.31 pounds in the case

21 8 SCIENCE AND PRACTICE OF CHEESE-MAKING

of the cheese made from the poorer milk and 5.31
pounds in the case of the cheese made from the
richer milk. When the cheese from the two milks
is made to contain the average amount of water
(37 per cent) found in green cheese, there is a
normal difference of 2 pounds of water in the
cheese made from 100 pounds of milk. What do
we find in regard to the yield of cheese and of
water in the cheese, when the yield of cheese is
calculated by method 3 ? The yield of cheese from
100 pounds of the poorer milk is increased 0.19
pound, from 8.90 to 9.09 pounds, an increase wholly

Pounds of
cHcese

Pounds

Pounds of

Per cent

(containing

of water

cheese for

water in

Per cent of

of fat

37 per cent
of water)
made for

in cheese

100 pounds

cheese

water in

casein

made

of milk

from 100

cheese cal-

milk

in mUk

from 100

calculated

pounds of

culated by

100 pounds
of milk

pounds

milk

method 3

of milk

method 3

(method 3)

3.26

2.20

8.90

3.31

9.09

3.50

38.50

5.78

3.03

14.36

5.31

13.93

4.88

35.00

due to the greater amount of water contained in
the cheese; the water increases from 3.31 to 3.50
pounds, and the percentage of water in the cheese,
from -^y to 38.50. In the case of the cheese made
from the richer milk, the reverse is found to be
true. The yield of cheese containing 37 per
cent of water is 14.36 pounds for 100 pounds of
milk, and this is decreased 0.43 pound or from
14.36 to 13.93 pounds. This decrease is wholly
due to the smaller amount of water in the cheese
when the yield is calculated by method 3. Thus,
the amount of water in the cheese containing 37

CALCULATING YIELD OF CHEESE 21 9

per cent of water is decreased from 5.31 to 4.88
pounds in the cheese calculated by method 3, and
the percentage of water from 37 to 35 per cent.
We see, therefore, that the difference of cheese
yield in these two cases should be normally 5.46
pounds for the cheese made from 100 pounds of
milk, but the difference is only 4.86 pounds, or
G.62 pound too small, when the yield is calculated
by method 3. (3) Another objection raised to
this method is that, under ordinary conditions, the
percentage of casein in milk is not known and the
method is consequently inapplicable. In reply to
this, the percentage of casein in milk can be calcu-
lated from the percentage of milk-fat and the method
carried out in the usual way. Even when the amount
of casein in milk is calculated, the results are gen-
erally much more accurate than those given by method
2 (i.i Fat+5.9).

METHOD BASED ON FAT AND SOLIDS-
NOT-FAT IN MILK (4)

In the twelfth annual report of the Wisconsin
experiment station there is a detailed discussion of
the facts leading to the proposal of the following
formula :

Yield of green cheese containing 37 per cent of
water

This formula is based on the following details: (i)
The am^ount of solids-not-fat in 100 pounds of milk,
divided by 3, represents the amount of milk-solids,
other than fat, available for cheese, including added

220 SCIENCE AND PRACTICE OF CHEESE-MAKING

salt in cheese; it therefore inckides milk-casein and
ash constituents. (2) The average amount of fat
lost in cheese-making is taken as 9 per cent of the
milk- fat and, consequently, 0.91 of the milk-fat is
calculated as being in the cheese. (3) In using the
factor 1.58, the cheese-solids are calculated to an
equivalent amount of cheese containing 37 per cent
of water. This method has been supposed to give
more accurate results than any of the preceding
methods.

The following objections to the method suggest
themselves : ( i ) It involves the accurate determina-
tion of the specific gravity of milk in addition to
the percentage of milk-fat. This ought not to be
a serious objection, but is found to be so practically
when cheese-makers try to find time to take the
necessary lactometer readings. (2) The formula is,
more complicated than any other, requiring more
extended arithmetical work, although entirely of a
simple kind. (3) The accuracy of calculating the
non-fat cheese-solids as equal to one-third of the
solids-not-fat of milk is not as close as is desirable,
because, when applied in the case of different milks,
the results are found to be quite irregular outside
of certain limits, to which attention will be called
later.

NEW METHOD BASED ON FAT AND
CASEIN IN MILK (5)

On account of difBculties experienced in applying
the methods under consideration with uniform and
accurate results, an efifort has been made, based on

CALCULATING YIELD OF CHEESE 221

the results of the work done at the New York ex-
periment station, to work out a method of deter-
mining cheese yield which should be simple and
at the same time more accurate than the methods
previously used. This method is based upon ( i )
the per cent of fat and of casein in milk; (2) a loss
of fat proportional to the amount of fat in milk,
based upon average results; (3) a uniform loss of
casein; (4) an amount of salts and albumin in cheese
proportional to the available fat and casein in
the milk; and (5) a uniform percentage of water in
cheese.

We will now briefly consider the details upon
which the method is based, under the two following
divisions: (i) Calculation of cheese-solids, and (2)
calculation of water in cheese. The amount of
solids in cheese is calculated by the formula,
(0.93 Fat-f- Casein — 0.10X1-09. This is based upon
the following details : ( i ) Of the fat in milk, 7 per
cent (0.07 pound for each pound of milk-fat) is lost
in whey and 93 per cent (0.93 pound for each
pound of milk-fat) remains in cheese (p. 190).
(2) Of the milk-casein, about o.io pound for 100
pounds of milk is lost, the rest going into the
cheese (p. 195). (3) The other constituents of
cheese-solids, consisting mostly of salts (p. 187),
form about 9 per cent fo.09) of the fat and casein
present in cheese. Therefore, if we multiply the
amount of fat and casein in cheese by 1.09 we ob-
tain the total amount of cheese-solids (fat, casein,
salts, etc.) in cheese. For example, suppose we have
milk containing 4 per cent of fat and 2.5 per cent of
casein, how many pounds of cheese-solids can be

222 SCIENCE AND PRACTICE OF CHEESE-MAKING

made from loo pounds of such milk? Using the
formula, we have [0.93X4 (fat)-j-2.5 (casein) —
o. 10] X 1 .09= (3.72+240) X 1 .09=6.67 pounds.

It remains now simply to calculate the cheese-
solids into cheese with a given percentage of water.
This can be done by subtracting from i.oo the per-
centage of water desired in the cheese, expressed as
hundredths, and then dividing by the result the solids
in the cheese, as obtained above. The formula, thus
amended, becomes :

(0.93 Fat + Casein — 0.10) X 1.09

100 — W (water- in cheese)

Continuing the illustration in which we have found
6.67 pounds of cheese-solids, we will suppose that we
wish to know how much cheese, containing 37 per
cent of water, can be made from this amount of
cheese-solids. We simply divide 6.67 by 0.63 (i.oo —
0.37), which gives 10.6 pounds. To find the equiv-
alent amount of cheese containing 35 per cent of
water, divide by 65 (i.oo — 0.35) ; for cheese con-
taining 40 per cent of water, divide cheese-solids by
0.60 (i.oo — 0.40).

If, then, we wish to have a method for calculating
yield of cheese when the cheese contains a definite
amount of water, say 37 per cent, which is the
average amount in green cheddar cheese, we can use
the formula :

(0.93 Fat + Casein — 0.10) X 1.09
0.63

This can be further simplified by dividing 1.09 by
0.63, when the formula becomes

(0.93 Fat+Casein — o.io)Xi-73.
In other words, find, in the manner indicated, the

CALCULATIXG YIELD OF CHEESE 223

amount of fat and casein that go into the cheese and
multiply by 1.73.

After satisfactorily applying the formula in this
form to a large number of cases, it occurred that
this might be used as a means of working out a
still simpler relation between the fat and casein
of milk and yield of cheese. Using the foregoing
formula for calculating the cheese yield with milks
covering quite a wide variation in percentages of fat
and of casein, it was found that the formula could be
simplified to the following form :

(5) (Fat-|-casein)X I -63=71616 of cheese
for 100 pounds of milk, the cheese containing 37 per
cent of water. Stated in the form of a rule, this
becomes : Add together the numbers representing the
percentages of fat and of casein in milk and multiply
the sum by 1.63.

From this formula, we can calculate in the fol-
lowing manner the equivalent amount of cheese
containing any percentage of moisture. Multiply
the cheese yield, calculated according to the last
formula, by 0.37; subtract this amount from the
weight of cheese and divide the remainder by i.oo
minus the number expressing the desired percent-
age of moisture. Expressed as a formula, this
becomes :

P (Number of pounds of cheese) — 0.37 P

100 — W (percentage of water desired^

For convenience, we have thus calculated a fac- '
tor which can be used directly in determining
cheese yield for each percentage of water from 30
to 50.

224 SCIENCE AND PRACTICE OF CHEESE-MAKING

SIMPLE METHOD OF CALCULATING
CHEESE YIELD FOR CHEESE CON-
TAINING DIFFERENT PERCENT-
AGES OF WATER

In order to obtain the amount of cheese yield con-
taining a given percentage of water, substitute the
number opposite the given percentage in the following
list for 1.63 in the last formula above given, which
would then become :

Yield=( Fat+ Casein) XN
(N being the number in the following list which cor-
responds to the percentage of water in cheese desired).

Per cent of water

Factor to be used

in cheese

as N in fonnula (Fat + casein) x

1.47

1.49

1.51

1.53

1.555

1.58

1.605

1.63

1.655

1.68

1.71

1.74

1.77

1.80

1.835

1.87

1.90

1.94

1.98

2.015

2.05

SIMPLE METHOD FOR CALCULATING

YIELD OF CHEESE FROM FAT AND

CALCULATED CASEIN

In connection with the foregoing method, which
is based in part upon the percentage of casein in
milk, it may be objected that the method cannot be

CALCULATING YIELD 01 CHEESE 225

applied when we do not know the percentage of
milk-casein. In reply to this, it can be stated that
fairly accurate results can be obtained by calculat-
ing the amount of casein in milk from the formula:
Per cent of casein in milk^(Fat — 3)Xo.4+2.i
(p. 170).

This formula can be combined with the follow-
ing formula: Cheese yield=(Fat-j-Casein)Xi-63
and the two operations of calculating casein and
cheese yield can be combined in one simple formula,
as follows :

(6) Cheese yield=2.3F-|-i.4.

Therefore, in multiplying the per cent of fat in milk
by 2.3 and adding 1.4 to the result, we obtain directly
the yield of cheese, containing 37 per cent of water,
based on the percentage of milk-fat and the amount
of casein corresponding to this percentage of fat, as
found by the milk-casein formula.

The yield of cheese corresponding to any per-
centage of water from 30 to 50 can be similarly cal-
culated. This is done by substituting for N in the
following formula one of the numbers in the last table
preceding, according to the desired percentage of
water: (1.4 Fat+o.QlXN.

METHOD OF CALCULATING YIELD OF

RIPE CHEESE

The amount of moisture in cheese when it
is sold for consumption necessarily varies with
a number of different conditions (p. 315) and an
effort to estimate the amount of cheese yield in
marketable condition is, to some extent, a matter
of guesswork, unless one knows something of the

226 SCIENCE AND PRACTICE OF CHEESE-MAKING

conditions of temperature, moisture, etc., under
which the cheese has been kept. However, it is
sometimes desired to know approximately the yield
of ripened cheese. We can assume (i) that the
green cheese contains an average per.centage of
water (37) and (2) that it loses 5 pounds of water
for 100 pounds of cheese. This would have the
effect of reducing the percentage of water in the
ripe cheese to- about 34. Therefore, the simplest way
to calculate the amount of ripe cheese, if the com-
position of the milk is known, is to multiply the sum
of the percentage of fat and casein in milk by 1.555;
or, when only the per cent of fat in milk is known, to
multiply the fat by 2..2. and then add 1.3.

COMPARISON OF ACCURACY OF DIF-
FERENT METHODS OF CALCULAT-
ING CHEESE YIELD

In making a comparative study of the accuracy
of the different methods that have been used or
proposed for calculating yield of cheese, the follow-
ing procedure was adopted : As a basis upon which
to work, there were taken 200 of the experiments
contained in the records of the New York experi-
ment station, which give full analyses of milk,
whey and cheese, and yields of cheese. The yields
of cheese as given were calculated to a uniform
basis of cheese containing 37 per cent of water.
The yield of cheese was then calculated according
to each one of the formulas that have been discussed.
In the case of the methods in which casein is a

CALCULATIN'G YIELD OF CHEESE 22^

factor, the yield of cheese was calculated both for
the actual amount of casein in the milk as obtained
by analysis and for the calculated amount of casein
as obtained by the casein formula. There were
thus compared, in reality, seven different methods.
It is impracticable to give these results in detail,
but it will be found sufficient to present them in
the form of tabulated summaries. It has been
found that the most effective means of compari-
son is to divide the experiments into several
groups based on the percentage of fat in milk, and
under each group to indicate the number of cases
in which the results differ, within certain limits,
from the actual yield of cheese. To illustrate, we
will take Group I (p. 228), including 22 experiments,
in which milk containing 3 to 3.49 per cent of fat was
used. In the case of method i (FatX2.7), there are
20 cases out of the 22 in which the calculated yield
of cheese is within 0.25 pound (4 ounces) of the
actual yield. There are 2 cases in which the calculated
yield is within 0.26 to 0.35 pound of the actual yield.
In the case of formula 2, there are only 5 cases in
which the calculated yield is within a quarter of a
pound of the actual yield, etc.

A study of the table on page 228 enables one to
observe the truth of the following statements :

The different methods in some cases show great
variation in respect to accuracy, according to the
composition of the milk. Thus, method i (FatX
2.7), which has usually been regarded as, perhaps,
the least accurate of any method in use, is found
to give most excellent results in the case of milks

228 SCIENCE AND PRACTICE OF CHEESE-MAKING

COMPARISON OF DIFFERENT METHODS FOR CALCULATING

CHEESE YIELD

1.1 Fat -f- 2.5

\ 4

Casein

o 'P

t/!

Group I

22 Exp'ts
Fat 3-3.49%

Variation
from

1.S

■2^

actual yield

rt
fo

cJ5

fo^ 5

0-0.25 lb.

0.26-0.35 lb.

0.36-0.50 lb.

, ,

0.51-0.75 lb.

, ,

0.76-1.00 lb.

. .

Group II

59 Exp'ts

Fat 3.50-3.74

0-0.25 lb.

0.26-0.35 lb.

0.36-0.50 lb.

0.51-0.75 lb.

. .

Group III

51 Exp'ts

Fat 3.75-3.99

0-0.25 lb.

0.26-0.35 lb.

0.36-0.50 lb.

0.51-0.75 lb.

, ,

0.75-0.99 lb.

. .

Group IV

43 Exp'ts

Fat 4.0-4.19

0-0.25 lb.

0.26-0.35 lb.

0.36-0 50 lb.

0.51-0.75 lb.

0.75-0.99 lb.

, ,

1.00-1.50 lb.

. .

• •

■ •

• •

Group V

25 Exp'ts

Fat 4.2-4.4

0-0.25 lb.

0.26-0.35 lb.

0.36-0.50 lb.

0.51-0.75 lb.

0.75-0.90 lb.

• •

, ,

1.00-1.50 lb.

varying in fat from 3.0 to 3.50 per cent, and compara-
tively fair results in the case of milks containing fat
up to 4.0 per cent. Method 2 (i.i Fat+5.9) gives

CALCULATING YIELD OF CHEESE 229

fairly good results in case of milks containing 3.50
to 3.75 per cent of fat, because the casein of such
milks is near the average upon which this formula
is really based (p. 215) ; but, outside of these nar-
row limits, it is the least accurate of all the methods
that have been used or proposed. In case of milk
containing 4.0 per cent of fat or more, the method is
entirely useless, in some cases varying from the
real yield of cheese i to 1.5 pounds. Method 3
(i.i Fat-|-2.5 Casein), when the actual amount of
casein is known, gives rather poor results in case of
milk below 3.5 per cent in fat, excellent results
when the per cent of fat in milk ranges from 3.5 to
4.0 per cent, fairly good results in case of milk con-
taining as high as 4.2 per cent of fat, but less accurate
with milks above this. Method 3, when the casein i?
calculated, gives results which are, in general, in ver)i
good agreement with those obtained when the
amount of casein is determined by chemical analysis.
Method 4

gives most excellent results when the milk con-
tains 3.50 to 4.0 per cent of fat, but in other cases
is, with the exception of method 2, the least accu-
rate of any examined. This method has heretofore
had the reputation of being, for all grades of milk,
the most accurate method in use. Method 5, when
the per cent of casein in milk is known, is seen to
be the most accurate method of all. When the
casein is calculated, method 6 gives excellent com-
parative results, the least satisfactory being in the
case of milks containing 3.50 to 3.75 per cent of

230 SCIENCE AND PRACTICE OF CHEESE-MAKING

fat. In the case of milks containing 3 to 3.50 per
cent of fat the results are most excellent.

The following table gives a summary of the results,
showing the percentage of cases in which the diiierent
methods are accurate within the limits designated,
taking all the 200 results into consideration without
reference to special groups in respect to percentage
of milk-fat :

Actual

Calculated

Actual

Calculated

casein

0-0.25

60.

42.5

66.5

62.5

57.5

62.5

0.26-0.35

17.

12.

14.

17.

18.

13.

0.36-0.50

15.5

19.5

12.

12.5

12.

12.5

0.51-0.75

13.5

6.5

8.5

10.

0.76-0.99

0.5

4.5

1.5

1.00-1.50

From these results, the relative values of the dif-
ferent formulas can be judged in a general, compara-
tive way. It is evident that method 2 (i.i Fat -{-5.9)
should not be used and that method 4,

^Solids-not-fat

+ .91 Fatlx 1.58

)

should, if employed at all, be used only in the case
of milks containing 3.5 to 4.0 per cent of fat. When
the percentage of casein in milk is known, only
method 5 (Fat-j-Casein) X1.63 should be used. In
case the casein has to be calculated from the per-
centage of fat in milk, then method 6 should be used.
For ordinary purposes method 6 will probably be
found to be the most useful, since the only factor
needed is the percentage of milk-fat and the calcula-
tion is extremely simple (2.^ FatH-i.4).

CHAPTER XIX

MOk Constituents in Relation to Compo-
sition of Cheese

While the yield of cheese from loo pounds of milk
depends, as has been shown (p. i86), upon the
amount of fat, casein and insoluble salts in milk, so
far as the cheese-solids are concerned, the percentage
composition of the cheese-solids depends practically
upon the relation of fat and casein in milk. Milk
rich in fat, as compared with milk poor in fat,
usually produces cheese containing more fat in pro-
portion to other constituents. The composition of
cheese depends primarily upon the composition
of the milk used, provided the process of cheese-mak-
ing is performed in a normal manner, so as to avoid
excessive loss of fat or casein. In this connection
we shall discuss the following points : ( i ) The rela-
tion of composition of milk to composition of
cheese (a) in case of normal milk, (b) in case
of skimmed milk, and (c) in case of milk containing
added cream. (2) The United States standard for
cheese.

MILK CONSTITUENTS AND COMPOSITION

OF CHEESE

Composition of cheese from normal milk. — The

composition of green cheese, in case of normal fac-
tory milk, as made in New York state, shows the

231

232 SCIENCE AND PRACTICE OF CHEESE-MAKING

following- range of variations and general average,
as the result of the extended investigations carried on
by the New York experiment station:

Lowest

Highest

Average

Water

32.69
56.11
30.00
20.80
3.12

43.89
67.31
36.79
26.11
7.02

36.84

Total solids

63.16

Fat

33.83

Proteins

23.72

Salts, etc. (represented in ash)

5.61

Percentage of solids in form of fat . . .
Ratio of fat to proteins

50.39
1:0.79

56.83
1:0.63

53.56
1:0.70

We can illustrate differences in composition of
cheese made from normal milk by taking cheese
made from the milk of different breeds of cows.
For this purpose, we will use the composition of
milk as given on p. 165 in case of four different
breeds :

Breed

Solids

Fat in

Proteins

cheese

Percentage

of total solids

in form

of fat

Ratio of

fat to
proteins

Holstein-Friesian

Ayrshire

Guernsey

Jersey

Per cent

63.00

34.1

23.6

63.00

34.5

23.3

63.00

37.0

20.8

63.00

37.5

20.4

54.3
54.8
58.7
60.0

Fat: Proteins

0.69
0.67
0.56
0.54

The difference in composition is very clearly
seen, especially if we notice the percentage of
'the cheese-solids present in the form of fat and the
ratio of fat to proteins as shown in the last two
columns. In connection with this table, study Fig.
37 (p. 208)..

MILK AND COMPOSITION OF CHEESE

233

The following" table extends the illustration sys-
tematically to ordinary milks containing different
percentages of fat. We may regard these as rep-
resenting milks of different herds. See also Fig. 36.

Per cent

of fat

in milk

3.00
3.25
3.50
3.75
4.50
4.25
4.50

Cheese-
solids

Fat in
cheese

Proteins
in cheese

Percentage
of total
solids in

form of fat

Ratio of

fat to
proteins

Per cent

63.00

33.7

24.1

34.1

23.7

34.5

23.3

34.8

23.0

35.1

22.7

35.4

22.4

35.7

22.1

53.5
54.0
54.6
55.2
55.7
56.2
56.7

Fat:
1
1;

i:
11
li

Proteins
0.72
0.70
0.68
0.66
0.65
0.63
0.62

These tables strikingly indicate that, as milk in-
creases in percentage of fat, the cheese made from
such milk increases in percentage of fat and de-
creases in percentage of proteins. The composi-
tion of the cheese-solids follows the composition of
the milk as shown in the relation of fat and pro-
teins.

Composition of cheese made from skimmed
milk. — The removal of fat from milk reduces the
amount of fat in relation to casein, because, in
skimming milk, only a relatively small amount of
casein is removed with the fat. The remaining
skim-milk is therefore richer in casein relative to
fat, the ratio increasing with the amount of fat
removed. The effect of skimming milk upon its
composition and upon the composition of cheese
is illustrated in the two following tables. The
data are based upon (i) normal milk containing 4
per cent of fat, (2) removal of fat alone without

234 SCIENCE AND PRACTICE OF CHEESE-MAKING

other constituents, (3) a uniform percentage of
casein in skim-milk, and (4) a uniform per cent (37)
of water in cheese. While the data represent
theoretical conditions, the results are not far from the
truth in practical application and they serve satisfac-
torily to illustrate the point we desire to impress In
connection with this table, study Fig. 38.

EFFECT OF SKIMMING MILK ON COMPOSITION OF MILK

AND YIELD OF CHEESE

Pounds of fat

Pounds of

Ratio of fat

Pounds

removed from

left in

casern m

to casein

100 pounds

skimmed

in milk

cheese

of milk

milk

Fat: Casein

Ct)— 0.00

4.00*

2.50

0.63

10.60

(2)— 0.50

3.50

2.50

0.71

9.79

(3)— 1.00

3.00

2.50

0.83

8.98

(4)— 2.00

2.00

2.50

1.25

7.37

(5)— 3.00

1.00

2.50

5.71

(6)— 3.90

o.iot

2.50

25.0

4 33

*Normal milk. tSeparator skim-milk.

EFFECT OF SKIMMING MILK ON COMPOSITION OF

CHEESE

Per cent of

Percentage of

Ratio of fat

Per cent of fat

proteins in

cheese-solids in

to proteins in

in cheese

cheese

form of fat

cheese

Fat: Proteins

(D— 35.1

22.7

55.7

1: 0.65

(2)— 33.3

24.5

53.0

1- 0.74

(3)— 31.1

26.7

49.4

1: 0.86

(4)— 25.2

32.6

40.0

l: 1.30

(5)— 16.1

41.7

25.5

1: 2.60

(6)— 2.3

55.5

3.7

I: 24.00

In making cheese from skim-milk, the yields
given are lower than those obtained in commercial

MILK AND COMPOSITION OF CHEESE

235

work, because here we allow for only 37 per cent
of water, while commercial skim-milk cheese never
contains so little moisture, but usually from 40 to
55 per cent, the moisture held in cheese increasing

FIG. 38 — DIAGRAM SHOWING EFFECT OF SKIMMING MILK
UPON THE YIELD AND COMPOSITION OF CHEESE

The figures immediately above each column give the number of pounds of
cheese fcontainintr 37 per cent of water) made from IflO pounds of milk. The fit>ures
within the diagram give the pounds of each constituent in cheese. The figures
at the top of the diagram give the percentage of fat in milk and skim-milk.

as the per cent of fat in skim-milk decreases. In com-
paring the results in this table with those in the
table on p. 232, in which the composition is shown
of cheese made from milk low and high in fat,
we see that the difference there is the same in

236 SCIENCE AND PRACTICE OF CHEESE-MAKING

character as that brought about by partially skim-
ming whole milk. For example, by skimming from
100 pounds of Jersey milk, containing 5,78 per cent
of fat, 1.25 pounds of fat, thus reducing the fat to
4.53 per cent, the resulting milk and cheese will then
be essentially the same in composition, in relation to
cheese-solids, as the normal Holstein-Friesian milk,
as shown by the following table :

•

Per cent
of fat

Per cent
of casein

Ratio of fat
to casein

Holstein-Friesian milk

Jersey milk (normal)

Jersey milk (partially skimmed)

3.26
5.78
4.53

2.20
3.03
3.03

Fat : Casein
1: 0.67
1: 0.52
1: 0.67

Of course, the same result could be accomplished
by adding skim-milk to milk rich in fat.

There is another way of comparing milks which,
like these, are poor and rich in fat. Thus, how
much fat would it be necessary to add to the Hol-
stein-Friesian milk to have it make "cheese like that
m.ade from Jersey milk? Calculation shows that
nearly one pound of fat would need to be added
to 100 pounds of the Holstein milk, which is thus
shown :

Fat in
milk

3.26

Fat added
-I 0.94

Per cent of fat
in enriched milk

4.20

Per cent of
casein in milk

2.20

Ratio of fat
to casein

Fat ; Casein
1: 0.52

It can, therefore, be seen that the differences ex-
isting between rich and poor milk are, so far as
relates to the composition of the cheese made from
them, such as can be adjusted by removing fat

MILK AND COAIPOSITION OF CHEESE

237

from the rich milk or adding skim-milk to it, or by
adding fat to skim-milk. The difference in milk
poor in fat which makes the fat go farther in mak-
ing cheese is a difference which may be character-
ized, in a general way, as a skim-milk difference,
because it depends upon a relatively high proportion
of casein.

Composition of cheese made from milk contain-
ing added cream. — Addition of cream to normal
milk affects the cheese made from such milk in a
way directly opposite to that produced by skim-
ming; that is, it increases the proportion of fat in
cheese in relation to proteins. A single illustration
will suffice. We give the composition of cheese
made from normal milk containing 4 per cent of fat
and also from the same milk after its fat content has
been increased to 6 per cent by the addition of
cream.

Per cent

of fat

in milk

Pounds of

cheese for

100 pounds

of milk

Per cent

of fat in

cheese

Per cent
of pro-
teins
in cheese

Per cent

ofcheese-

solids in

form

of fat

Ratio of

fat to

proteins

#Iormal milk. .
Enriched milk

4.00
6.00

10.60
13.80

35.1

40.4

22.7
17.4

55.7
64.0

Fat:
Proteins
1: 0.65
1: 0.43

THE UNITED STATES CHEESE STANDARD

At this point it seems desirable to call attention
to the standard of purity adopted for cheese by the
United States Department of Agriculture in con-
nection with the national pure-food law. Its defi-
nition of cheese made from normal or whole-milk is as

22^^ SCIENCE AND PRACTICE OF CHEESE-MAKING

follows : "Standard whole-milk or full-cream cheese
contains, in the water-free substance, not less than
50 per cent butter-fat." There has been wide-
spread and needless misunderstanding in regard to
the meaning of this standard. Many have inter-
preted it as meaning that normal or whole-milk
cheese must contain 50 per cent of fat. The law
does not say that at all, but that 50 per cent, not of
the cheese, but of its water-free substance (cheese-
solids) must consist of butter-fat. This can easily
be made clear by giving a specific illustration of
its application, and, for this purpose, we take a ched-
dar cheese of average composition, containing:

Water 36.80 per cent.

Water-free substance 63.20 ..

Consisting of (100.00)

Fat 33.75

Proteins. . .23.75
Salts, etc... 5.70

••

63.20

In order to apply the standard to any cheese, we
need to know only the percentages of water and
of fat. One then proceeds as follows : Subtract
the percentage of water from lOO, which gives the
cheese-solids or water-free substance, and then
divide the percentage of fat in cheese by the per-
centage of water-free substance. Expressed in out-
line, the statement becomes: (i) lOO minus per cent
of water=per cent of water-free substance; (2) per
cent of fat-^per cent of water-free substance=
per cent of fat in water-free substance. Example :
(i) 100 — 36.80 (per cent of water in cheese)=
63.20 (water-free substance in cheese). (2) 33.75
(per cent of fat in cheese)-^63. 20^53.4, which is the

MILK AND COMPOSITION OF CHEESE 239

per cent of fat in the water-free substance of the
cheese. In order that a cheese be below standard,
the fat must be less than one-half of the water-free
substance. In this particular case, the cheese would
be below standard if the fat were less than 31.60
per cent.

The question naturally arises as to what actual
basis there is for such a specific standard. It is
based upon very extensive studies of cheese made
from normal milk. The work of the New York ex-
periment station with cheese made in New York
factories has shown that the fat is always more
than one-half of the total solids or water-free sub-
stance of cheese. In the case of the lowest result,
the percentage was 50.39; the highert. 5C.83 ; and
the average, 54. In very few cases was the per-
centage of fat in cheese-solids found below 51.0.
These results are in agreement with those obtained
in other states. For example, in the Wisconsin
cheese-scoring contests for April, May, June and July
(1908), results are given, showing that, even in the
cheese poorest in fat, the fat was 51.35 per cent of
the water-free substance. The percentage of fat in
the water-free substance of the cheese varied from this
figure to 56.4 as the highest.

In addition to the results of analysis of many
samples of cheese made from normal milk, the
composition of normal milk itself furnishes a good
reason why the fat should amount to more than
one-half of the water-free substance of cheese ;
since a study of normal milk, as it Is found at
cheese-factories In New York state, shows that
such milk does not contain enough casein, relative

240 SCIENCE AND PRACTICE OF CHEESE-MAKING

to fat, to make cheese of composition such that its
water-free substance contains less than 50 per cent
of fat, provided, of course, there is no abnormal
loss of fat in the process of cheese-making. For
example, it can readily be seen from the table on
p. 234 that normal milk containing 4 per cent of
fat can suffer a loss of nearly one-fourth of its fat,
before the composition of the cheese drops below
standard. Normal milk containing 3.50 per cent
of fat can be reduced to about 3 per cent of fat
before the cheese made from it contains less than
50 per cent of fat in its water-free substance.
Ordinary milk containing 3 per cent of fat could
have its fat reduced nearly to 2.75 per cent before
making cheese below standard. These facts go to
show that the United States standard is well above
the limits of danger for cheese properly made from
normal milk.

Another question in connection with the cheese
standard may be asked : Why not use as a standard
t^e percentage of fat in the cheese itself in-
stead of in the water- free substance? The present
standard has for its purpose, the prevention of the
use of skimmed milk for making cheese lor be sold as
normal or whole-milk cheese. It does not aim to con-
trol the amount of moisture in cheese. If the
percentage of fat in cheese were used as a standard,
then the amount of water in cheese would become
an important factor; because the greater the mois-
ture content of cheese, the less the percentage of fat
in the case of cheese made from milk of the same
composition. It is recognized that different markets
call for different percentages of water in cheese

MILK AND COAIPOSITION OF CHEESE 24I

and, by basing the cheese standard on the water-
free substance of the cheese, this condition has not
been interfered with.

Some of the state cheese standards. — In some
states there are laws which aim to set up various
standards according to the percentage of fat in
cheese, having one percentage of fat for whole-milk
cheese, another for partial-skim, another for half-
skim and another for full-skim. Such provisions
are cumbersome in legal administration, as well
as demoralizing to the best interests of the cheese
industry and deserve only severe condemnation.

It is interesting to notice the legal provisions for
cheese standards which are or have been in force
in some states. In California full-cream (whole-
milk) cheese must contain 30 per cent of fat; half-
skim 15 per cent of fat; while full-skim cheese is
any cheese made from skim-milk. Under these
provisions it would be easily possible to make no
normal-milk cheese, since all the cheese intended
to comply with the requirements for so-called "full-
cream" might be made from partially . skimmed
milk. In Colorado 35 per cent of the cheese-solids
(water-free substances) must be fat. This is 15
per cent below the United States standard. Under
such a provision normal milk containing 4.0 per
cent of fat could have one-half of its fat removed
before the cheese would drop below the Colorado
standard as given above. Under such circum-
stances it would be a miracle if Colorado had an
ounce of cheese made from normal milk except
for the saving condition that the actual relation
of such a standard is probably not clearly under-
stood by Colorado cheese-makers and surely not

242 SCIENCE AND PRACTICE OF CPIEESE-MAKING

by her legislators, it is to be hoped. In Minnesota,
the law has required that 45 per cent of the
cheese-solids be fat, which is too low. In Missouri,
the only provision has seemed to be that the cheese
should be made from milk containing not less than
3 per cent of fat. In Ohio, cheese containing less
than 20 per cent of fat is skim-cheese. This is
certainly a very generous allowance, since cheese
made from normal milk rarely contains less than
'}^2 per cent of fat even when green. It is to be
hoped that the provisions in these states for whole-
milk cheese have been or will be changed to
conform with the provisions of the United States
pure-food law.

Misleading use of terms describing cheese. — The

foregoing discussion impresses one with the unfor-
tunate use of certain words in describing cheese
made from normal milk or whole-milk. The ex-
pressions, ''full-cream," "factory-cream," etc., while
in common commercial use, and clearly understood
by those who use them, are misleading to one who
interprets their meaning at their face value. Ap-
parently, such terms imply normal milk contain-
ing added cream. The use of the word cream in
any form to describe normal milk is a relic of the
inaccurate knowledge of former generations, and
should be abandoned in the interests of clearness and
precision. Whole-milk or normal milk is in every
respect a much better expression to use in describing
cheese made from milk that is normal.

CHAPTER XX

The Composition of Cheese ii\ Relatioi^

to Quality

In the preceding chapter it has been demon-
strated that cheese made from milk rich in fat
contains relatively and actually more fat and less
proteins than cheese made from milk poor in fat.
Two such cheeses, made with equal skill, the milk
being uniform in every way except in composition,
show a marked difference in commercial quality
(p. 244) ; and the one having the larger percentage
of fat would be declared to be superior in quality.
This has been demonstrated in practical ways by
the experiment stations of Wisconsin, Iowa, Min-
nesota and New York; and their work, the first to
be done along these lines, has been supplemented
and confirmed by the work of others. It has been
found generally true that cheese made from milk
containing added cream is superior in flavor and tex-
ture to that made from ordinary normal milk; and
that made from normal milk is superior in flavor, tex-
ture, body and keeping quality to cheese made from
skim-milk.

Variation in quality in cheddar cheese follows
more or less closely the relation of fat to proteins
in cheese ; the larger the proportion of fat, the bet-
ter, in general, the quality of cheese and the
higher the market value. This fact is, of course,
associated with, and dependent upon, the function

243

244 SCIENCE AND PRACTICE OF CHEESE-MAKING

that milk-fat performs in cheese, that of imparting
smoothness of feeHng, mellowness of body, rich-
ness and delicacy of taste and palatability. Bear-
ing on this particular point, the late Henry E.
Alvord makes the following statement (Yearbook
of U. S. Dept. of Agr., 1895, P- 47^) • ''Other things
being equal, a cheese containing a large percentage
of fat is better, because, first, of finer flavor and
taste; second, of its better consistency; third, of its
improved aroma ; fourth, of its increased digestibility ;
fifth, of its more perfectly answering the requirements
of a complete food or 'balanced' ration.' " In this
connection, it is interesting to learn that in Germany
the custom of selling cheese according to the per-
centage of fat contained in it is rapidly coming into
use.

While the view expressed above is very generally
held and is based upon experimental work, there
have been no extensive commercial opportunities for
demonstrating the matter in a systematic way.
But some valuable facts bearing on this point in a
most * direct and practical form have just been
developed in the four Wisconsin cheese-scoring
contests held during April, May, June and July,
(1908). The facts are all the more interesting be-
cause they are merely incidental to the general pur-
pose of these contests. The method of conducting
these competitive tests in Wisconsin cannot be too
highly recommended to other states, especially be-
cause very full details are given, unusual under
such circumstances, making the work of peculiar
value in enabling one to study relations existing

CHEESE COMPOSITION AND QUALITY

245

between the composition of cheese and its commei-
cial value. In each of these monthly scorings, it is
significant that the cheese scoring highest contained
the largest amount of fat relative to proteins, while
the cheese scoring lowest in every case contained the
lowest amount of fat relative to proteins, as shov/n
by the following data :

Cheese scoring highest

Cheese scoring lowest

Per cent
of fat

Per cent

of
proteins

Ratio of

fat to
proteins

Per cent
of fat

Per cent

of
proteins

Ratio of

fat to
proteins

April
May..
June.
July.

Fat:prot'ns

36.

27.

1: 0.75

32.

29.2

35.25

27.4

1: 0.78

35.

29.2

35.

27.5

1: 0.79

34.5

29.8

35.

29.46

1: 0.84

34.3

29.3

Fat;
1:
1:
1;
1;

prot'ns
0.91
0.83
0.86
0.86

The most striking difference is shown by the
April results, the least by those of July. In study-
ing all the available data, the only apparent cause
that accounts for these differences is the difference
in composition. In the case of some of the cheeses
that were scored second and third below the high-
est, as compared with others that were scored second
and third from the lowest, the general relation of
quality and composition was shown but not equally
in every case. While these results do not in them-
selves absolutely prove the relation between composi-
tion and commercial quality, their special value is that
they confirm, in a different way, the results of other
work.

It cannot fail to be of value in the discussion of
this subject to present the views of some of those

246 SCIENCE AND PRACTICE OF CHEESE-MAKING

who have been generally regarded as authorities in
relation to the commercial as well as to the scientific
aspects of cheese-making. For this purpose, we
have chosen to give the views (i) of Dr. Robert-
son, so long Canada's most efficient leader in the
progress of all branches of dairying and especially
of cheese-making, and (2) of Dr. Babcock, who
has been properly regarded as America's leading
student of dairying in its scientific relations and
who has given special attention to the question
under discussion.

In the Report of the New York Dairymen's
Association for 1891, we find the following state-
ments in an address given by Dr. Robertson : "In
every case there was a gradual reduction in the
quantity of cheese when there was a less quantity
of butter-fat in milk. . . . However, this is
true also, that the increased yield of cheese is not
in direct proportion to the increased percentage
of butter-fat; that is, milk containing 3 per cent
of butter-fat will yield a certain quantity of cheese,
but if you take milk having one-third more fat (4
per cent) it will not yield one-third more cheese.
At the same time, such milk is zvorth one-third more
for cheese-making, and thereby hangs a tale. You
see, if it does not yield so much cheese, it makes a
quality of cheese so much better that the market value
of the cheese from too pounds of milk is a third
greater than the market value of the cheese in the
other case" (pp. 198-199). ''Every two-tenths of a
pound of butter-fat will improve the quality of the
cheese one-eighth cent per pound, as near as I can

CHEESE COMPOSITION AND QUALITY 247

find out. Thus, you have a difference of about five-
eighths of a cent per pound between cheese made
from 3 per cent and 4 per cent milk" (p. 201).

Dr. Babcock approaches the question from quite
another point of view (Report of New York Dairy-
men's Association for 1892, pp. 150, 153, etc.).
After showing that fat is the constituent controlUng
the value of milk, cream and butter, he says : "It is
evident that the market price of milk, of cream and of
butter depends chiefly upon the price of butter-fat,
and that other constituents have so little influence that
they can practically be neglected.

''There is one other important dairy product to be
considered, and that is cheese. Does the same prin-
ciple hold with this? I believe it does, for on no
other basis can I reconcile market prices all over the
world."

He then goes on to show by actual market quo-
tations that cheese varies in price according to
its richness in fat, all the way from 11 cents per
pound for whole-milk, fancy cheese down to i to
'zYz cents a pound for full-skim cheese. Antici-
pating some objections raised to the method of
reasoning as applied to the fat basis as a method
of paying for milk at cheese-factories, he con-
tinues: ''I cannot leave this subject without refer-
ring to some of the objections made to its use In
cheese-factories. It is urged that because casein
and fat are intimately mixed together in cheese,
they bring the same price per pound when sold,
and so should be given the same price in calculat-
ing the value of milk that is to be used for this pur-
pose. If this is true, the water which comprises a

248 SCIENCE AND PRACTICE OF CHEESE-MAKING

larger proportion of cheese than the casein should
be treated in the same way, and worthless constit-
uents in any product should have the same value
as the mixture in which they occur. It is absurd,
on the face of it, as it gives entirely different values,
to the same constituent according to the product
considered. It makes the casein, water and fat
worth each about one cent per pound in milk, the
same constituent worth 30 cents per pound in but-
ter and anywhere from i to 11 cents per pound in
cheese, according to the proportions in which they
are mixed. Whereas, the relative value plan gives
consistent values in all.

"Again, it is said that the life-sustaining power
of a pound of casein is about the same as a pound
of fat, and that they should therefore have about
the same value; but it must be borne in mind that
the nutritive value and the market value of foods have
no relation to each other. You can buy nutrients
in corn meal cheaper than you can in wheat flour.
Maple sugar costs you two or three times as much
as beet sugar, although the two have identically
the same efifect. All of these things are con-
trolled by the universal law of supply and demand,
and have nothing to do with their relative food
value.

"When any article has a high value for any
special purpose, that fixes the price which must
be paid for it for all other purposes. You cannot
afford the use of rosewood or mahogany for fuel,
not because they have less heat-producing power
than maple or birch, but because they command a
higher price for piano cases or other articles of

CHEESE COMPOSITION AND QUALITY 249

furniture. The general public esteems butter-fat more
highly than casein and are willing to pay a much
higher price for it. It is folly to stand in your own
light and argue that this is inconsistent."

These arguments of Dr. Babcock are based on
general economic truths which hold good to-day as
fully as when they were stated by him. They are
facts which should be kept in mind when considering
the relation of composition of cheese to commercial
quality or market value. In the 12th annual report
of the Wisconsin experiment station (p. 115), Dr.
Babcock also says :

*Tt is a well-established fact that rich milk gives
a better quality of cheese, which commands a higher
price, than that from poor milk."

We add also the following quotation from an
address given before the Wisconsin cheese-makers'
convention at Milwaukee, in 1907, by Prof. E. H.
Harrington, dairy husbandman at the Wisconsin ex-
periment station : "It will be seen that the richer the
milk, the better the price per pound of cheese
made from it. I am occasionally asked if 100
pounds of milk testing 6 per cent of fat will make
twice as much cheese as 100 pounds of milk test-
ing 3 per cent of fat. The answer to this question
is briefly that the cheese made from the richer
milk is of much better quality and worth a higher
price per pound than that made from the thinner
milk, and this will help balance any difference in
yield. The influence of the richness of milk on
the quality of cheese is something that should
not be lost sight of in considering the question of

250 SCIENCE AND PRACTICE OF CHEESE-MAKING"'

paying for milk at a cheese-factory by the Babcock
test."

SKIM-MILK CHEESE

The manufacture of skim-milk cheese has been
fostered and protected in some of our states. There
are some considerations worthy of our attention in
connection with the discussion of the composition of
cheese in relation to quality.

(i) The removal of fat from ordinary normal
milk, such as the mixed milk of our cheese-fac-
tories, results in producing- cheese that differs in
composition from whole-milk cheese. Such cheese,
as we have seen, contains less fat and more casein
than that made from normal milk having the same
percentage of fat. Skim-milk cheese is an adul-
terated food product, according to the legal defini-
tion of adulteration.

(2) It is impossible to remove fat from ordi-
nary normal milk without affecting the composi-
tion of the cheese unfavorably, and along with
this, the quality as well. While skim-milk cheeses
may differ from one another in composition and
quality, they are all inferior to whole-milk cheese
properly made from normal milk of good quality in
all respects.

(3) Skim-milk cheese is not only deficient in
fat, but it always contains an abnormally high
percentage of water. This is absolutely necessary
in order to make it edible and have it appear in
body and general quality as a good imitation of
whole-milk cheese. A skim-milk cheese containing

CHEESE COMPOSITION AND QUALITY 25 1

only the amount of water held by a whole-milk cheese
would be practically unsalable on account of its
hardness and toughness. High percentages (50-55)
of water are necessary in order to make the cheese
appear to contain fat and have a smooth-feeling
body.

(4) Skim-milk cheese, on account of its high per-
centage of water, dries out very rapidly under ordinary
conditions in the hands of the consumer and becomes
inedible, though it can then be used by experts in some
forms of cooking.

(5) Skim-milk cheese, on account of its high per-
centage 01 water and of proteins, does not possess
the keeping qualities of whole-milk cheese. It
develops undesirable flavors more easily and does not
have the same length of life under the same condi-
tions, especially when kept at temperatures above
60° F.

(6) Skim-milk cheese generally becomes digestible
less readily than whole-milk cheese kept under the
same conditions ; and when its proteins become rapidly
soluble, offensive flavors usually develop, destroying
its value.

(7) The retail price of skim-milk cheese is always
too high in comparison with whole-milk cheese.
Separator skim-milk cheese usually sells at retail for
10 cents a pound, when whole-milk cheese sells for i6
cents. Such skim-milk cheese sells for more than
three times its real value.

(8) The consumer is not really protected, even
when an attempt is made by the state to do so.
How many people want or even ask for skim- milk
cheese? The average consumer is ignorant of

252 SCIENCE AND PRACTICE OF CHEESE-MAKING

systems of branding or other methods devised for his
protection. He simply asks for cheese and takes what
is offered. It should be made as dangerous for re-
tailers to sell skim-milk cheese for whole-milk cheese
as it is for them to sell imitation for pure butter.

(9) The indiscriminate sale of skim-milk cheese
inevitably injures the sale of whole-milk cheese.

( 10) Skim-milk, consumed as such or in the form
of cottage-cheese, is a more economical and nutritious
food than when used as skim-milk cheese.

(11) There is a strong inclination on the part of
those interested in the cheese industry to believe that
the real interests of dairymen and of the general public
would be best protected and promoted by the absolute
prohibition of skim-milk cheese, as demonstrated by
Canada.

CHAPTER XXI

Methods of Paying for Milk for
Cheese-Making

The subject relating to methods of paying for
milk at cheese-factories has been one of more or
less constant discussion for about twenty years.
Shortly before the year 1890, some question was
raised as to the fairness of paying for milk at
cheese-factories by weight. Two factors worked
against the realization of any practical results
coming from such discussion : ( i ) Lack of knowl-
edge regarding the relation of milk-constituents to
yield and quality of cheese, and (2) the need of
a practicable method for determining any of the
cheese-making constituents of milk. In 1890 Dr.
Babcock furnished his method of determining fat
in milk, and then the discussion soon centered
about the use of fat in milk as a basis for paying
for milk used in cheese-making. The application
of the test in the case of butter-making was at
once understood and utilized ; but, in connection
with cheese-making, it was known that two con-
stituents are concerned, fat and casein, and the
question was therefore more complicated than in
the case of butter-making, where only fat was con-
cerned. During the years 1891 to 1895, ^ large
amount of investigation was carried on, which re-
sulted in giving us such a comprehensive and sys-

253

254 SCIENCE AND PRACTICE OF CHEESE-MAKING

tcmatic knowledg-e of the relations of milk constitu-
ents to cheese as had not been possible previously.
In oreneral, it was shown that, while the amount of
fat in milk is not an absolute guide in respect to
the yield of cheese from milks containing- differ-
ent amounts of fat, it is a very much more accurate
index than the mere weight of milk; and that,
while, in case of milks containing higher percent-
ages of fat, the yield of cheese is usually less for
a pound of milk-fat than in the case of milk con-
taining lower percentages of fat (p. 207 j, the cheese
made from the richer milk is of more excellent
quality and has a higher commercial value (pp.

243-249).

The fat basis began to be introduced into actual
cheese-factory work about 1892, and its use spread
(|uitc ra])idly during the next few years. This
method was at first received with considerable en-
thusiasm. After a few years a reaction gradually
took place and the system was abandoned in many
factories, which went back to the old method of pay-
ing for milk by weight only. There are several reasons
why the fat basis in paying for milk for cheese-mak-
ing has experienced its ups and downs, like every
other reform movement, and we will notice some of
the most prominent of these.

(i) Wherever the fat basis replaced the weight-
of-milk method, the change affected the dividends of
different patrons in different ways. Those furnish-
ing milk containing percentages of fat above the
average received more money for their milk, while
those furnishing milk containing percentages of

PAYING FOR MILK FOR CHEESE-MAKING 255

fat under the average found their dividends re-
duced. Therefore, the owners of cows giving milk
low in fat were bitterly disappointed and exercised
their ingenuity in discovering reasons why the fat
basis was objectionable and unfair. This attitude
of the producer of poor milk is, of course, the
fundamental reason why the fat basis has been
abandoned in some cases where it had been intro-
duced. The other objections raised were subordinate
to this one, though some of them had, perhaps, some
real basis.

(2) The reliability of the Babcock test was
attacked and the accuracy of its results called into
question. The points of objection raised on this
ground were, (a) that the Babcock method of
testing milk for fat is unreliable under all circum-
stances; (b) that, while the method, when properly
handled, is accurate, cheese-makers are careless
or inefficient in operating the test, and their results
are therefore inaccurate; (c) that the glassware
was not always accurately graduated and conse-
quently gave incorrect results; (d) that cheese-
makers deliberately gave some patrons higher
results than those indicated by the test. The gen-
eral charge of inaccuracy of the test itself was,
of course, prompted by ignorance or malice or both.
There was probably once some justification for the
charge of carelessness and inefficiency against
operators of the Babcock test ; for it was un-
doubtedly true to some extent that cheese-makers
attempted to employ the method who had not been
properly instructed in its use nor acquired the
requisite accuracy of manipulation. There was at

256 SCIENCE AND PRACTICE OF CHEESE-MAKING

one time a strong disposition to over-emphasize
the extreme simphcity of the Babcock test and to
lose sight of the fact that even so simple a method
requires careful attention to every detail and that
certain precautions must be strictly observed. It
was also true that some manufacturers became care-
less and put on the market glassware that was inac-
curate. This difficulty has been effectively overcome
in most of the prominent dairy states by an official
testing of all graduated glassware used in the Babcock
test, before it is placed on sale.

(3) Many cheese-makers object to the added work
involved, even when paid for it. An unwilling
cheese-maker can easily influence patrons against the
method.

(4) Another cause for the discarding of the fat
basis in many cases was the confusion introduced
by proposing some modification of the method in the
interest of the producer of poorer milk, a point which
we will consider more fully later.

In the history of the cheese-making industry, we
can distinguish in the order of their appearance, five
methods which have been proposed for the purpose
of paying for milk at cheese-factories:

(i) Weight of milk.

(2) Amount of fat in milk.

(3) Relative values of fat and other cheese-solids
based on yield and composition of cheese.

(4) Modification of fat basis to include part of the
milk-casein.

(5) Amount of fat and casein in milk.

We will now consider each of these methods as to
their comparative merits and defects.

PAYING FOR MILK FOR CHEESE-MAKING 257

PAYING FOR MILK ON BASIS OF WEIGHT

Under this system each patron receives the same
amount of money for each lOO pounds of milk de-
livered at the factory. This method possesses the
advantage of simpHcity and economy of time, in-
volving no additional work. Among the disadvan-
tages of this method are the following : ( i ) It
assumes, as a fundamental basis of its fairness,
that all kinds of normal milk have the same cheese-
producing value; that, from lOO pounds of any
milk, we make the same amount of cheese. This
assumption has been abundantly proved not to be
true, since the yield of cheese from lOO pounds of
milk may (p. 207) vary all the way from 8 to 13
pounds or more. The method is, therefore, unfair
to the producers of milk containing higher per-
centages of fat. (2) This system discourages the
production of milk of higher percentage in fat.
When weight alone is considered in making pay-
ment, more money can be received by increasing
the amount of milk produced, without regard to
its composition ; and it is thus found more profit-
able to produce milk as low in fat as legal require-
ments permit. .(3) This system breeds criminality,
because it encourages the addition of water, re-
moval of cream and all similar forms of dishonesty.
Some dairymen have regarded the direct addition
of water to milk as the most economical way of
increasing milk production for cheese-making pur-
poses, but the experience is not usually attended
with most economical results for any length of
time.

258 SCIENCE AND PRACTICE OF CHEESE-MAKING

However much difference of opinion there may
exist in regard to the efficiency of different methods
of paying for milk for cheese-making, all who are
in position to give a reliable judgment in the matter
agree on this one point, viz., among the various
methods proposed, this one is farthest from doing
justice to all producers of milk.

PAYING FOR MILK ON BASIS OF FAT

When milk is paid for on the basis of its fat content,
each patron receives the same amount of money for
each pound of fat in the milk delivered. For example,
the patron whose milk contains 3 per cent of fat
receives payment for 3 pounds of fat for each 100
pounds of milk delivered by him ; while the patron
whose milk contains 4 per cent of fat receives pay-
ment for 4 pounds of fat for each 100 pounds of milk
furnished by him. The second patron receives one-
third more per 100 pounds of milk than the first one,
while, under the weight-of-milk method, each would
receive an equal sum. This can be illustrated as
follows :

For the sake of simplicity, we will compare the
milks furnished by two patrons, one milk con-
taining 3, and the other 4, per cent of fat. We
will assume that the cheese sells for 10 cents a
pound. We will make the comparison on the basis
of 100 pounds of milk, allowing that the cheese
yield from 100 pounds of milk containing 3 per
cent of fat is 8.30 pounds, and from milk contain-
ing 4 per cent of fat, 10.60 pounds, a total of 18.90
pounds, bringing 189 cents. By the weight-of-milk
method, this sum is divided equally between the

PAYING FOR MILK FOR CHEESE-MAKING

259

two patrons, because each furnishes the same
amount of milk. Hence, each receives 94.5 cents
for the cheese made from his milk. On this basis
the one furnishing milk containing 3 per cent of
fat receives 11. 4 cents a pound for each pound of
cheese made from milk furnished by him; while the
other receives 8.9 cents for each pound of cheese made
from his milk.

Dividends based on the percentage of fat in milk
are made as follows: One patron furnishes 3
pounds of fat and the other 4. There are, all
told, 7 pounds of fat, the cheese corresponding to
which sells for 189 cents. Therefore, each pound
of fat is credited with 2y cents; one patron re-
ceives 81 (27X3) cents and the other, 108 (27X4)
cents. In this case the one furnishing the poorer
milk receives 9.76 cents a pound for the cheese
made from his milk, and the other, 10.19 cents. The
existing difference, 0.4 cent a pound, is generally
held to represent an actual difference in the quality
and value of the cheese (p. 246). These results
can be very well shown in the following tabulated
form:

Weight-ot-Milk Method

MUk-Fat Basis

Pounds

of fat

in 100

pounds

of mUk

Pounds
of cheese

made

from 100

pounds

of milk

Divi-
dend

Money

rec'd for

each

pound

of
cheese

Money
rec'd for
each
pound
of milk-
fat

Divi-
dend

Money

rec'd for

each

pound

of cheese

Money
rec'd for
each
pound
of milk-
fat

Cents

8.30

94.5

11.4

31.5

9.76

10.60

94.S

8.9

23.6

108

10.19

260 SCIENCE AND PRACTICE OF CHEESE-MAKING

Of the various objections deserving any atten-
tion, which have not been already noticed, the fol-
lowing are the chief ones urged against this
method :

(i) The percentage of fat in milk is not gen-
erally an accurate measure of the amount of cheese
made from lOO pounds of milk. A pound of fat in
milk containing 3 per cent of fat represents more
cheese than does a pound of fat in milk containing
4 per cent of fat; in the former case, the cheese yield
is 2.^^ pounds for one pound of fat in milk, while in
the latter it is 2.65 pounds. On this- account, the milk
containing least fat does not receive pay for all the
cheese it makes.

(2) The cost of making the test is often raised as
an objection. In actual practice, the difficulty has
been satisfactorily overcome. The usual custom is
to pay the cheese-maker at the rate of 20 to 25 cents
a month for each patron.

The principal reasons given for favoring the fat
basis are the following:

( 1 ) This method recognizes the fundamental truth
that normal milks varying in percentage of fat possess
dififerent values for cheese-making.

(2) The amount of fat in milk offers a practicable
and just basis for determining the cheese-producing
value of milk, when we consider both quality and
quantity (p. 246).

(3) All temptation to adulterate milk by water-
ing or skimming is absolutely removed, since a
man receives pay for the number of pounds of fat
that he furnishes and not merely for the number of
pounds of liquid he carries to the factory. No other

PAYING FOR MILK FOR CHEESE-MAKING 26l

method now in use so completely eliminates the
temptation to adulterate milk.

(4) This method promotes improvement in the
character of milk production. This is not merely a
theoretical statement but has been proved to be true
in practice. It offers an inducement to each dairyman
to improve the composition of his milk.

(5) Improvement in the character of dairy animals
and in the consequent yield and composition of milk
means economy of production and increase of profit.
Cheese-solids in rich milk can be produced at less cost
than in poor milk.

(6) This method awakens interest in the subject
of milk production, stimulates a desire for further
knowledge and tends to place the production of milk
on a higher plane of intelligence.

PAYING FOR MILK ON THE BASIS OF

YIELD AND RELATIVE VALUE OF

CHEESE-SOLIDS

In the twelfth annual report of the Wisconsin
experiment station (pp. 114-119), Dr. Babcock has
worked out a system of payment by which the
yield of cheese and composition are both taken
into consideration. The principles embodied in
this method have not received the general attention
deserved. "It is not sufficient for a system to give
the true yield from each patron's milk, for this
makes skim-milk cheese equally valuable with that
from the richest milk. The perfect system of
making dividends in cheese-factories must include,
not only the amount, but also the relative values

262 SCIENCE AND PRACTICE OF CHEESE-MAKING

of fat and the other cheese-producing solids ; with
such a system each patron will receive his just pro-
portion whether he brings skim-milk, watered milk
or cream." His proposed method gives to milk-
fat a value of 6.6, as compared with a value of i.o
for the cheese-solids not fat. The following table

Per

Lactometer Degrees

Per

cent

fat

2.0

2.86

2.88

2.89

2.91

2.93

.2.94

2.96

2.98

3.00

3.01

3.03

2.0

2 1

2.98

3.00

3.01

3.03

3.05

3.06

3.08

3.10

3.12

3.13

3.15

2.1

2.2

3.10

3.12

3.13

3.15

3.17

3.18

3.20

3.22

3.24

3.25

3.27

2.2

2,3

.» '-

3.24

3.25

3.27

3.29

3.30

3.32

5.34

3.36

3.37

3.39

2.3

2.4

J. 34

3.36

3.37

3.39

3.41

3.42

3.44

3.46

3.48

3.49

3.51

2.4

2.i

3.47

3.49

3.50

3.52

3.53

3.54

3.5^

3.58

3.60

3.61

3.63

2.5

2.6

3.59

3.61

3.62

3.64

3.65

3.67

3.69

3.71

3.73

3.74

3.76

2.6

2.7

3.71

3.73

3.74

3.76

3.77

3.79

3.81

3.83

3.85

3.86

3.88

2.7

2.8

3.83

3.85

3.86

3.88

3.90

3.91

3.93

3.95

3.97

3.98

4.00

2.8

2.9

3.95

3 97

3.98

4.00

4.02

4.03

4.05

4.07

4.09

4.10

4.12

2.9

3jO

4.07

4.09

4.10

4.12

4.14

4.15

4.17

4.19

4.21

4.22

4.24

3.0

3.1

4.19

4.21

4.22

4.24

4.26

4.27

4.29

4.31

4.33

4.34

4.36

3.1

3.2

4.31

4.33

4.34

4.36

4.38

4.39

4.41

4.43

4.45

4.46

4.48

3.2

3.i

4.43

4.45

4.46

4.48

4.50

4.51

4.53

4.55

4.57

4.58

4.60

i.z

3.4

4.55

4.57

4.58

4.60

4.62

4.63

4.65

4.67

4.69

4.71

4.72

3.4

3.5

4.68

4.70

4.71

4.73

4.75

4.76

4.78

4.80

4.82

4.83

4.85

i.i

3.6

4.80

4.82

4.83

4.85

4.87

4.88

4.90

4.92

4.94

4.95

4.97

3.6

3.7

4.92

4.94

4.95

4.97

4.99

5.00

5.02

5.04

5.06

5.07

5.09

3.7

3.8

5.04

5.06

5.07

5.09

5.11

5.12

5.14

5.16

5.18

5.19

5.21

3.8

3.9

5.16

5.18

5.19

5.21

5.23

5.24

5.26

5.28

5.30

5.31

5.33

3.9

4.0

5.29

5.31

5.32

5.34

5.36

5.37

5.39

5.41

5.43

5.44

5.46

4.0

4.1

5.41

5.43

5.44

5.46

5.48

5.49

5.51

5.53

5.55

5.56

5.58

4.1

4.2

5.53

5.55

5.56

5.58

5.60

5.61

5.63

5.65

5.67

5.68

5.70

4.2

4.3

5.65

5.67

5.68

5.70

5.72

5.73

5.75

5.77

5.79

5.80

5.82

4.3

4.4

5.77

5.79

5.80

5.82

5.84

5.85

5.87

5.89

5.91

5.92

5.94

4.4

4.5

5.89

5.91

5.92

5.94

5.96

5.97

5.99

6.01

6.03

6.04

6.06

4.5

4.6

6.02

6.04

6.05

6.07

6.09

6.10

6.12

6.14

6.16

6.17

6.19

4.6

4.7

6.14

6.16

6.17

6.19

6.21

6.22

6.24

6.26

6.28

6.29

6.31

4.7

4.8

6.26

6.28

6.29

6 31

6.33

6.34

6.36

6.38

6.40

6.41

6.43

4.8

4.9

6.38

6.40

6.41

6.43

6.45

6.46

6.48

6.50

6.52

6.53

6.55

4-9

5.0

6.50

6.52

6.53

6.55

6.57

6.58

6.60

6.62

6.64

6.65

6.67

5.0

6.62

6.64

6.65

6.67

6.69

6.70

6.72

6.74

6.76

6.77

6.79

5.1

6.74

6.76

6.77

6.79

6.81

6.82

6.84

6.86

6.88

6.89

6.91

5.2

5.3

6.86

6.88

6.89

6.91

6.93

6.94

6.96

6.98

7.00

7.01

7.03

5.3

5.4

6.98

7.00

7.01

7.03

7.05

7.06

7.08

7.10

7.12

7.13

7.15

5.4

5.5

7.10

7.12

7.13

7.15

7.17

7.18

7.?0

7.22

7.24

7.25

7.27

5.5

S.6

7.23

7.25

7.26

7.28

7.30

7.31

7.33

7.35

7.37

7.38

7.40

5.6

5.7

7.35

7.37

7.38

7.40

7.42

7.43

7.45

7.47

7.49

7.50

7.52

5.7

5.8

7.47

7.49

7.50

7.52

7.54

7.55

7.57

7.59

7.61

7.62

7.64

5.8

5.9

7.59

7.61

7.62

7.64

7.66

7.67

7.69

7.71

7.73

7.74

7.76

5.9

6.0

7.71

7.73

7.74

7.76

7.78

7.79

7.81

7.83

7.85

7.86

7.88

6.0

PAYING FOR MILK FOR CHEESE-MAKING 263

is worked out, based on yield of cheese and relative
value of cheese-solids for milks containing different
percentages of fat from 2 to 6. Values are given which
can be used directly in the same manner as the per-
centages of fat are used in case of the fat basis.
These values appear to be qmte accurate, especially
for milks containing 3.5 to 4.0 per cent of fat.
The only additional labor required is to apply the
lactometer to a sample of each milk and take the
reading. ''This modification would give to each
patron the same amount of money which he would
obtain if his milk were manufactured by itself. In
this respect it differs widely from those modifica-
tions of the relative-value plan which aim to make
dividends in proportion to the pounds of cheese
which each milk will produce, leaving out entirely
the quality of the cheese." Tlie following illustration
shows the application of this method:

One patron furnishes milk showing by test 3
per cent of fat and a lactometer (Quevenne) read-
ing of 28; another, milk with 4 per cent of fat and
a lactometer reading of 34. Turning to the preced-
ing table, it is found that milks corresponding to
these percentages of fat and lactometer readings
have relative values for cheese-making represented
by the numbers 4.10 and 5.43. To find the dividend
of each, we divide the amount of money (189 cents)
received, by the sum (9.53) of these two num-
bers, which gives 19.83. This number multiplied by
4.10 and 5.43 gives the respective dividends of the
two patrons.

264 SCIENCE AND PRACTICE OF CHEESE-MAKING

Pounds of

fat in

100 pounds

of milk

Pounds of

cheese made

from 100

pounds of milk

Dividend

Money rec'd

for each

pound of

cheese

Money rec'd
for each
pound of
milk-fat

8.30
10.60

Cents

81.3

107.7

9.80

10.16

Cents
27.10
26.92

By comparing these results with those given by the
simple fat basis (p. 259), and other methods, we see
that the values are much closer to the results of the
fat basis than by any other method.

Application of principle to fat and casein. — This
same principle could be readily applied when we
know the percentages of fat and of casein in milk.
We might be even more liberal and, instead of al-
lowing only one-sixth for casein, allow as much
as one-fourth. In this case, the dividends would
be based on the fat plus one-fourth of the casein
in each case. This is illustrated in connection with
the fat and casein method of making dividends (p.
270).

MODIFICATION OF FAT BASIS KNOWN AS
THE "FAT-PLUS-TWO" METHOD

By this method the percentage of fat in milk is
increased by 2 and the results used as in making
dividends on the fat basis. The method originated
in Canada. The first suggestion was made about
1893, when at one of the cheese-factories the plan
was adopted of adding i to the fat in making divi-
dends, because it was noticed that this method
more closely approximated the cheese yield than

PAYING FOR MILK FOR CHEESE-MAKING

265

the use of fat alone. This method was made a sub-
ject of study at the Ontario Agricultural College and
was modified by adding 2 to the fat in making
dividends.

The dividends are made in the following manner
under this method, using the illustration already
given (p. 258) for milks containing 3 and 4 per cent
of fat. The receipts from sale of cheese are 189 cents.
Instead of one patron receiving three-sevenths and the
other four-sevenths of this amount, one receives
five-elevenths and the other six-elevenths, as shown
thus:

3+2=5
4+2=6

The results, compared with those of the fat basis,
are as follows for this particular illustration :

Pounds

of fat

in 100

pounds

of milk

Pounds
of cheese

made

from 100

pounds

of milk

Fat-Basis method

Fat-plus-2 method

Divi-
dend

Money
received
for each

pound
of

cheese

Money
received
for each

pound

milk-fat

Divi-
dend

Money
received
for each

pound
of

cheese

Money
received
for each

pound

of
milk-fat

Cents

8.30

9.76

10.36

28.7

10.60

108

10.19

103

9.72

25.7

This method is based on an attempt to approxi-
mate yield of cheese as a basis to use in paying
for milk. It is supposed that the addition of 2 to

266 SCIENCE AND PRACTICE OF CHEESE-MAKING

the per cent of fat makes allowance for the casein
of the milk, and, therefore, that milks which are
low in fat will get such a proportion of casein as
will balance the difference existing between milk
poor in fat and milk rich in fat in respect to yield
of cheese per pound of fat; and that, therefore,
taking the casein into consideration along with the
fat will give us a more accurate relation in regard
to yield of cheese and percentage of fat in milk.
This ought to be true and is true to a certain degree.
So far as we do take casein into consideration, we
get just that much nearer to the average of cheese
yield, speaking of yield alone and not considering
quality.

The objections which have been brought against this
method are the following:

(i) It does not recognize any casein in milk
above 2 per cent; it would be a fair measure of
yield of cheese if all milks contained 2 per cent of
casein, no more and no less. This is, of course,
not in accordance with the actual facts. The addi-
tional amount of casein above 2 per cent, which is
usually found in richer milks, is wholly ignored by
this method. For example, under this method, milk
containing 4 per cent of fat would, after adding 2,
be given a value of 6, whereas it should be given a
value of 6.4 or 6.5 or more on the basis of its usual
casein content.

(2) This method is, therefore, in the interest of
milk low in fat. It gives undue advantage to
poorer milk, and, to the same extent, works against
the producer of richer milk. It has been generally
held that too much encouragement cannot be given

PAYING FOR MILK FOR CHEESE-MAKING 267

to farmers to produce milk of richer composition.
In the illustration given above, one fails to see the
justice of a method which gives to the producer of
poorer milk 10.36 cents a pound for his cheese and
to the producer of richer milk, only 9.72 cents a
pound for cheese that is better if the milk is made
into cheese by itself.

(3) This method ofifers a premium on watering
milk, because the percentage of fat in milk (high
or low) is credited with only 2 per cent of casein;
and, hence, the lower the percentage of fat, the
larger will be the relative amount of casein and
the greater the price received for each pound of fat.
For example, a patron furnishing milk with 4 per
cent of fat could add, say, 33 pounds of water to
100 pounds of milk, thus reducing the percentage
of fat to 3. He would then have the benefit of
the added factor for 133 pounds of milk instead of
100 pounds. He would thereby increase his dividend
from 103 to 108 cents.

(4) This method also offers a premium on
skimming as well as watering milk. This can best
be made clear by illustration. A patron who
furnishes milk containing 4 per cent of fat skims
it so as to make it contain 3 per cent and then
adds enough water to make the weight of milk
100 pounds again. The cheese made from 100
pounds of such milk would be about 8.9 pounds.
The milk of the other patron, who furnishes 100
pounds of normal milk containing 3 pounds of fat,
makes 8.3 pounds of cheese, a total of 17.2 pounds
for the 200 pounds of mixed milk. This, we assume,
sells for 172 cents and is evenly divided between

268 SCIENCE AND PRACTICE OF CHEESE-MAKING

the two patrons, because each furnishes milk con-
taining 3 per cent of fat. Each, therefore, receives
86 cents. If the patron who produces milk with 4
per cent of fat takes the normal milk to the factory,
he receives on the "fat-plus-two" basis 103 cents, as
we have already seen. If he skims his milk as de-
scribed above, he receives 86 cents, or 17 cents less;
but he has, as an offset to this, one pound of milk-fat
which he can sell for 25 cents to 30 cents. There-
fore, he is the gainer by all that he can get for his
pound of milk- fat over 17 cents.

(5) This method, in opposition to the teachings of
Robertson, Babcock and many others, wholly ignores
the fact that composition and quality vary with fat
in milk and that cheese made from richer milk is of
higher value.

While these objections hold good, still the *'fat-
plus-two" method is unquestionably a great ad-
vance over the old weight-of-milk method. The
most unfortunate feature about this method is the
confusion which its introduction has caused among
dairymen. Instead of regarding it as a modifica-
tion of the fat basis, dairymen have, in many cases,'
thought that the whole principle of paying for milk
by any other method than the weight-of-milk
system was under suspicion. Dairymen do not
yet understand the details of different methods
clearly enough to discriminate, and, when they
are told that the fat basis is unreliable and in-
accurate, they most naturally lose confidence in
all methods based on the fat-test and go back to
the weight-of-milk system. Those who produce
poor milk take advantage of such an opportunity

PAYING FOR MILK FOR CHEESE-MAKING 269

to upset the entire system based on the fat-test.
Thus, the whole situation has been needlessly con-
fused, rather than benefited, for the average cheese-
factory patron.

PAYING FOR MILK ON BASIS OF FAT AND

CASEIN

By this method the percentages of fat and casein
in each patron's milk are added and the figures
thus obtained are used in apportioning dividends,
as in the fat basis. This can be illustrated as fol-
lows:

We will make use of the figures already
employed in illustrating the other methods. One
patron furnishes milk containing 3 per cent of fat
and 2.1 per cent of casein; the other, milk with
4 per cent of fat and 2.5 per cent of casein. Each
furnishes 100 pounds of milk; the total amount of
cheese made is 18.9 pounds, realizing 189 cents.
We add together the amounts of fat and casein in
the two. milks, obtaining 11. 6 as the total number
of pounds of fat and casein in the 200 pounds of
milk. The total amount of money received for the
cheese is divided by the total amount of casein and
fat, which gives us 16.3 cents as the value of each
pound of mixed fat and casein in milk. The divi-
dend of the patron furnishing the poorer milk is
16.3X5-1, which equals 83 cents; the dividend of
the other is 16.3X6.5, which equals 106 cents. In
this case, each receives the same price for the
cheese, 10 cents a pound, but not the same for milk-
fat; the poorer milk receives 27.7 cents a pound

270 SCIENCE AND PRACTICE OF CHEESE-MAKING

for its fat; the richer milk, 26.5 cents. Below are
given in tabulated form the results of this and other
methods already considered, and also the modification
of the fat-and-casein basis, in accordance with the
relative-value suggestions of Dr. Babcock ; that is, we
allow full value for fat and one-fourth value for
casein (p. 264).

Per zent
of fat

in
milk

Per cent

casein

in mdk

pounds

of
cheese

Divi
dend by
fat and

casein

Divi-
dend by

fat
method

Dividend

by fat and

one-fourth

casein

(P. 264)

Dividend

by"fat-l-2"
method

Cents

2.1

8.30

2.5

10.60

106

108

107

103

The fat-and-casein method has the following ad-
vantages :

( 1 ) It is an accurate measure of the yield of cheese
in the case of all kinds of milk when the losses of milk
constituents are not excessive.

(2) The temptation to adulterate by watering is
entirely removed.

The following disadvantages suggest themselves:
(i) Assuming that a test for casein gives results
as accurate as the Babcock test for fat in the hands
of ordinary cheese-makers, it is objected that the test
involves extra labor on the part of the cheese-maker,
for which he cannot well afiford the time. The same
objection is often made against the Babcock test, and
it would, of course, be much more forceful in regard
to a casein-test.

(2) An extra test involves additional cost,
even in case a cheese-maker could find time to

PAYING FOR MILK FOR CHEESE-MAKING 27I

make both fat and casein tests. If a cheese-maker
were paid on Uhe basis of what is received for
making fat-tests, it would amount to $50 or $60 a
season for most cheese-factories. To this must be
added cost of materials and breakage of glassware,
which might be conservatively placed at $10 to $15.
There would thus be a total outlay on the part of the
patrons amounting to $60 to $75 for the season in
having the casein-test made.

(3) The fat-and-casein method does not recog-
nize any difference in the value of cheese made
from milk high and low in percentage of fat. It
places the market value of casein on an absolute
level with milk-fat, while Dr. Babcock gives milk-
fat in cheese a value 6.6 times that of casein (p.
262).

(4) The use of the fat-and-casein method offers
a temptation to remove fat from milk or to add
skim-milk, in case of milk to be used for cheese-
making. To illustrate, casein in skim-milk has a
market value for the dairyman not to exceed 2 or
3 cents a pound, while milk-fat is worth about 30
cents a pound. In good cheese, casein and fat
together bring about 18 cents a pound. If casein
is paid for on a par with fat, then by adding skim-
milk to normal milk, one can increase the price of
his skim-m'ilk casein about nine times. The same
would be true if fat were removed from milk and
sold as butter or cream. In whatever manner one
increases the ratio of casein to fat in milk, he in-
creases the dividend value of casein in cheese-making,
when fat aji-d- casein are treated as of equal value in
making dividends.

2^2 SCIENCE AND PRACTICE OF CHEESE-MAKING

(5) The fat-and-casein method requires more time
in calculating dividends.

(6) Some have expressed the fear that, under
this system, the increased vakie of casein would
lead dairymen to breed cows for milk high in casein,
and that this would result in a poorer quality of
cheese and general consequent danger to die cheese
industry. In fact, the use of cows giving milk with
a high casein content has been specifically empha-
sized by some as a desirable end to work for and
it is urged that such an aim would be realized by
the recognition of casein in cheese-making as of
equal value with fat. Assuming that the percent-
age of casein in milk could be notably increased in
an economical manner, what would be the result?
By referring to pages 231-237, it can readily be
seen that the process would be nothing more or
less than a system of adding skim-milk to normal
milk, thereby increasing the amount of casein in
milk relative to fat. This fact is probably not
fully appreciated by those who are advocating the
process. We have probably reached the limits of
safety, in more than one sense, in many strains of
Holsteins and Ayrshires, as regards the high re-
lation of casein to fat. We do not need to spend
time and energy to breed cows for milk in the
direction of skim-milk for cheese-making. Some
progressive dairymen are, happily, still so old-
fashioned in their ideas as to advocate the opposite
process, viz., increasing the yield of fat in milk
without paying any attention to its skim-milk con-
stituent, casein. This is simply raising the old
question that used to be discussed so much 20 years

PAYING FOR MILK FOR CHEESE-MAKING 273

and more ago regarding the "butter cow" and the
"cheese cow." Thus, in the 1892 report of the
Vermont experiment station (pp. 122, 123), this whole
question is ably discussed, the article closing as
follows : "The logical conclusion, then, is that the
so-called 'cheese cow,' that is, the cow which is
especially good for cheese rather than for butter,
does not exist, and that whenever a cow is found
that is good for cheese-making purposes, the milk
of that cow is equally good for the manufacture of
butter." The following statement is found on page
471 of the 1895 yearbook of the United States De-
partment of Agriculture, in an article by the late
Henry E. Alvord : "Cumulative evidence is un-
necessary. These important truths are established,
namely: The best milk makes the best cheese, and
the most of it; the milk which is most profitable
for butter is also the most profitable for cheese ;
the best butter cow is the best cheese cow." In a
discussion of the same subject, Bulletin No. 9 of
the New Hampshire station contains the following
statements : "We are told that cows which are
giving milk poor in fat and are therefore poor but-
ter cows are great cheese cows. ... A milk
rich in fat is not only a good milk for butter but
also a good milk for cheese, while the reverse is also
true."

In harmony with the general tenor of the pre-
ceding statements, the investigation carried on with
dififerent breeds of cows at the New York experi-
ment station appears to demonstrate clearly that a
pound of cheese-solids can be produced at less

274 SCIENCE AND PRACTICE OF CHEESE-AIAKING

cost in case of milk rich in fat than in case of milk
poor in fat.

(7) Another highly important question has
been raised in connection with the use of a casein-
test in paying for milk at cheese-factories — Is it
worth the time and trouble expended on it? It
is not worth the time, if, with Dr. Robertson, Dr.
Babcock and others, we believe that casein is not
equal in value to fat for cheese production in rela-
tion to composition and quality of cheese. If, on
the other hand, we believe that yield of cheese
alone should be considered and that fat and casein
are of equal value, pound for pound, in cheese pro-
duction, even then we can ask the question — Are
the differences caused by variation in casein worth
the trouble and expense involved in making a
casein-test in addition to fat? To what extent
-"'U dividends be readjusted among patrons and
L ./nat manner? While this question can not
be answered finally until results have been secured
in numerous factories, we have sufficient data on
hand to give a definite answer in the case of one
representative New York factory for one season.
We have fat and casein determinations during one
factory season for each of 50 different herds of
cows whose milk was taken to one cheese-factory.
The analyses of milk were made every other week
for each herd separately from May to October in-
clusive. In 23 cases, the fat-and-casein method
gave a larger dividend than did the fat alone by
an average of 1.6 cents for each 100 pounds of milk,
the greatest difference in the case of any one patron
being 5.9 cents, and the least o.i cent. In one

PAYING FOR MILK FOR CHEESE-MAKING 275

case, both methods gave the same result. In 26 cases,
the fat method gave higher results by an average
of 1.4 cents for 100 pounds of milk, the difference
varying in the case of different individuals from 5.1
cents to 0.1 cent.

The greatest difference found in favor of the
fat and casein basis, 5.9 cents per 100 pounds of
milk, would mean for an entire factory season
nearly $20, assuming that this patron furnished
33,600 pounds of milk, an average of 224 pounds
for 150 days, which was the actual average for
each patron. Summarizing the results on this basis,
we have 2'^ men receiving more money by the fat-
and-casein method, amounting altogether, for the
season, to $123.46, the increased dividends of each
varying from 33.6 cents to $19.83, and averaging
$5-39- As a matter of fact, about two-thirds of the
money would go to 8 patrons. One patron re-
ceives the same amount either way. The remain-
ing 26 patrons receive less by the fat-and-casein
method than by the fat basis, amounting altogether
to $123.46, varying from 33.6 cents to $17.13, and
averaging $4.75 each.

On the basis of the estimated cost of $60 to $75
spent in paying for the test, more than half of the
difference ($123.46) would be used up, so that, if
those who benefited by the casein-test paid for it,
there would be distributed not more than half of
the amount above given. This would mean an ex-
penditure of $60 to $75, in order to adjust a dif-
ference of $123 in the interest of 23 men who fur-
nish milk which tests below the average in fat.
The entire sum involved amounts to less than 0.4

276 SCIENCE AND PRACTICE OF CHEESE-MAKING

per cent of the factory's receipts from cheese.
Under such circumstances, it is not at all likely
that the 2y patrons would vote to employ the fat-
and-casein method in distributing dividends, nor is
it likely that most of the 2^^ men benefited would
ask it, when the high relative cost of making a
redistribution was understood. While the results
represent only one cheese-factory, the conditions
are typical of those prevailing in New York state,
and results that are strikingly different from these
would probably be exceptional. If the dividends
were made on the basis of allowing less for casein
than fat, as recommended by Dr. Babcock (p. 264),
the difference in favor of the patrons furnishing
extra casein would be less than one-quarter what
they are when we allow the same price for casein
as for fat. On such a basis, the difference would
be only about half the cost of making the casein-
tests.

PAYMENT ON BASIS OF FAT AND CAL-
CULATED CASEIN

In view of the fact that so many cheese-fac-
tories are still paying for milk on the basis of
weight alone, as a result of the confusion that has
been created in regard to the fairness of the fat
basis, a method might be suggested which would
find use in factories that are now using no test
system, which would be far superior to the weight-
of-milk method and at the same time possess certain
advantages over other modifications of the fat
basis. Such a method would be to pay on the basis

PAYING FOR MILK FOR CHEESE-MAKING 277

of the fat and of the casein calculated according to
the formula, (Fat — 3)Xo.4+2.i. Such a method
is not recommended where the fat basis is being
used, but only as a compromise where it comes to
a choice between some such basis and the weight-
of-milk method; in other words, where the preju-
dice against the fat basis is too strong to be over-
come. The amount of casein obtained thus is
added to the fat and the dividends calculated in the
manner given on p. 284. The use of a method
basing dividends on the fat-test and the amount of
calculated casein would possess the following ad-
vantages :

(i) It would be preferable to the fat-and-casein
method, which requires two separate tests to be made,
since no test would be needed for casein, but only
for fat. It would, therefore, involve no additional
expense of time, labor or money, as is the case with
the casein-test.

(2) It would be more fair than the "fat-plus-
two" method, because milk containing higher per-
centages of fat would receive payment for the in-
creased amount of casein that goes with that
increased percentage of fat, instead of receiving
credit for only 2 per cent of casein, rich and poor
milks alike. This method gives results that are in
most cases much closer to the yield of cheese than
the *'fat-plus-two" method.

(3) The watering or skimming of milk could not
afifect the results, because the casein is made to depend
on the fat content. In this respect the method is
much superior to the fat-and-casein or the fat-plus-
two method.

2yS SCIENCE AND PRACTICE OF CHEESE-MAKING

(4) No more labor need be involved than in
the case of the fat basis, either in the matter of
testing or in the matter of calculating dividends.
The matter can be simplified by the consultation of
a table, which can be made out once for all. The
following formula can be used in preparing such
a table:

(Fat — 3)Xi4+5-io=Amount of fat and casein in
100 pounds of milk.

Such a table, already prepared, is here given :

Per cent of

Dividend

Per cent of

Dividend

fat in milk

number

fat in milk

number

3.00

5.10

4.05

6.57

3.05

5.17

4.10

6.64

3.10

5.24

4.15

6.71

3.15

5.31

4.20

6.78

3 20

5.38

4.25

6.85

3.25

5.45

4.30

6.92

3.30

5.52

4.35

6.99

3.35

5.59

4.40

7.06

3.40

5.66

4.45

7.13

3.45

5.73

4.50

7.20

3.50

5.80

4.55

7.27

3.55

5.87

4.60

7.34

5.60

5.94

4.65

7.41

3.65

6.01

4.70

7.48

5.70

6.08

4.75

7.55

3.75

6.15

4.80

7.62

3.80

6.22

4.85

7.69

3.85

6.29

4.90

7.77

3.90

6.36

4.95

7.84

3.95

6.43

5.00

7.90

4.00

6.50

(5) The introduction of the fat-test is called for
by this method, and thus a great step in advance
would be made in compari.son with the weight-of-
milk method. This might ultimately lead to the adop-
tion of the simple fat basis.

The following objections to such a method may be
suggested :

PAYING FOR MILK FOR CHEESE-MAKING 279

(i) It aims to pay for the amount of cheese
produced without regard to composition or quahty.
Of course, this same objection apphes to the fat-and-
casein method and the fat-plus-two method.

(2) The method of calculation may give
amounts of casein differing from those actually
present in milk. In individual cases and for single
tests, this might be true, but, taking the average
of a whole season, the differences would not
usually be found great, and the season's average
would be the factor on which to base a comparison
as to accuracy. As a matter of fact, in the case
of the 50 herds already referred to, in no case was
there a difference in the season's results greater
than 0.25 per cent of casein between the calculated
amount and that obtained by the chemical method ;
while in the case of 40 out of 50 patrons the results
aiffered by less than o.i per cent, in several cases
being identical. The casein-test, even in skillful
hands, may give results that differ as much as 0.2 per
cent from the regular chemical method.

METHODS OF CALCULATING DIVIDENDS
AT CHEESE-FACTORIES

In concluding this chapter, we will illustrate
somewhat more in detail how dividends at cheese-
factories are calculated according to the different
methods that have been discussed. For this pur-
pose, we will make use of the following data which,
for convenience, are given here in a body for refer-
ence. In all cases, the following three items must
be known: (i) The amount of milk delivered by

280 SCIENCE AND PRACTICE OF CHEESE-MAKING

each patron during the dividend period; (2) total
or gross amount of money received for the cheese
produced during the same period; and (3) the ex-
penses to be deducted from gross receipts, such as
cost of manufacture, cheese-boxes, cartage, selHng,
etc.

Name

of
patron

Pounds of milk
delivered dur-
ing dividend
period

Pounds of

cheese for

100 pounds of

milk

Per cent

of fat

in milk

Per cent

of casein

in milk

Pounds of
cheese made

from milk
delivered by
each patron

A
B
C
D

350
650
835
965
1200

10.6
9.7
13.3
11.5
11.1

4.0
3.6
5.2
4.4
4.2

2.50
2.34
2.98
2.68
2.58

37.1

63.0

111.0

133.2

Totals

4000

455.3

From the stated amounts of milk there are made
455.3 pounds of cheese. We will suppose that this
is sold at a price which realizes 10 cents a pound,
or $45.53, after all expenses are deducted.

Calculating dividends on basis of weight of milk.
— In the table preceding we have a total of 4,000
pounds of milk furnished in the dividend period
and the cheese made from this nets $45.53. Divid-
ing this sum of money by the number representing
the pounds of milk delivered (4,000), we find the
net receipts from i.o pound of milk to be 1.138
cents. This amount is multiplied by the number
representing the pounds of milk furnished by each
patron and the result gives the amount of the divi-
dend of each. The results are given in the following
table :

PAYING FOR MILK FOR CHEESE-MAKING

281

Pounds

Value

Divi-

of cheese

Money

Money re-

^JaTne

Pounds

of 1.0

dend of

made from

received

ceived for

of milk

pound

each for

milk fur-

for each

each pound

patron

delivered

of milk

period

nished by
each

pound of
cheese

of milk-fat
fiu-nished

Cents

350

1.138

$3.?8

37.1

10.73

28.4

650

1 1

7.40

63.0

11.75

31.1

835

«C

9.51

111.0

8.57

21.9

965

10.98

111.0

9.90

25.9

1200

13.66

L33.2

10.26

27.1

The figures in the last two columns emphasize the
fact that this method of paying for milk gives results
that have little or no relation to the cheese-produc-
ing values of the milk. It is fair to all only when
the milk furnished by each patron is of the same
composition and cheese-producing value as the milk
of every other patron, a condition rarely, if ever, found
to exist.

Calculating dividends on basis of fat in milk. —
Having the data already given above in the table on
p. 280 we multiply the amount of milk-fat delivered
by each patron by the net price realized for one pound
of fat. We will consider the method in three separate
steps.

Step I. To find the number of pounds of milk-fat
furnished by each patron, multiply in each case the
weight of milk by the number indicating the per cent
of fat and divide the result by 100.

Step 2. Find the net value of one pound of milk-
fat by dividing the total net receipts by the total num-
ber of pounds of fat delivered by all the patrons
during the dividend period.

282 SCIENCE AND PRACTICE OF CHEESE-MAKING

Step 3. Multiply the number of pounds of fat de-
livered by each patron by the net price received for one
pound of fat.

Example: Step i. The data and results are indi-
cated in tabular form, as follows :

Name of
patron

Pounds of milk
delivered during
dividend period

Per cent

of fat

in milk

Pounds of fat

in milk

delivered

350
650
835
965
1200

X 4.0
X 3.6
X 5.2
X 4.4
X 4.2

= 14.00

= 23.40

= , 43.42

= 42.46

= 50.40

Total number of pounds of fat deliver

ed by all patrons . .

173.68

Step 2. From the amount of milk indicated above,
the amount of cheese made was 455.3 pounds, which
realized 10 cents a pound after deducting all ex-
penses, making a total of $45.53. This sum divided
by 1^3.68, the total pounds of fat delivered, gives
26.2 cents as the net price received for each pound
of fat.

Step 3. The data and results are indicated in
tabular form, as follows :

Name of
patron

Pounds
of fat
delivered

Net price re-
ceived for fat
per pound

Amount of

dividend due

each patron

Net price re-
ceived for
cheese per lb.

14.00
23.40
43.42
42.46
50.40

Cents
X 26.2
X 26.2
X 26.2
X 26.2
X 26.2

= $ 3.67
6.14
= 11.38
= 11.13
= 13.21

Cents
9.90

B.:::

9.75

10.25

10.03

9.92

PAYING FOR MILK FOR CHEESE-MAKING

283

Calculating dividends on basis of yield and rela-
tive value of cheese-solids. — By this method one
proceeds exactly as in case of the fat-basis method,
except that in place of the percentages of fat, one
uses the number obtained from the table (p. 262) cor-
responding in each case to percentage of fat in milk
and the lactometer reading.

Calculating dividends on basis of milk-fat plus
two. — The following table indicates the general method
of procedure :

Name

of
patron

Pounds
of milk

de-
livered
during
divi-
dend
period

Per cent of
fat in milk
+ 2 (casein)

Pounds
of fat

and
casein

fur-
nished
corre-
spond-
ing to
fat + 2

Price

of each

pound

of fat

and
casein

Amount
of divi-
dend
due
each
patron

Net
price re-
ceived

for
cheese

per
pound

Net
price re-
ceived
for fat

per
pound

350

650

835

965

1200

Cents

(4.0x2=)6.0

= 21.0

X 17.95

= $3.77

10.16

(3.6x2 = )5.6

= 36.4

X 17.95

= 6.54

10.40

(5.2x2=)7.2

= 60.1

X 17.95

= 10.78

9.71

(4.4x2 = )6.4

= 61.8

X 17.95

= 11.10

10.00

(4.2X2=)6.2

= 74.4

X 17.95

= 13.34

10.02

Cents
27.0
28.0
24.8
26.1
26.5

In explanation of the foregoing table, it is seen
that the amount of milk furnished by each patron is
multiplied by the per cent of fat plus two. These
results are added and the sum (amounting to
253.7) <Jivided into the amount of money received
for the cheese ($45.53), giving 17.95 cents as the
value of each pound of mixed fat and casein (rep-
resented by 2 pounds of casein in 100 pounds of
milk). The number, obtained in each case by mul-
tiplying the number of pounds of milk furnished by

284 SCIENCE AND PRACTICE OF CHEESE-MAKING

the number representing the per cent of milk-fat-[-2,
is then multiphed by 17.95, the result being the
dividend in each case. It is noticed that this method
makes a pound of cheese or of milk-fat yield larger
money returns in case of poor than in case of rich
milk.

Calculating dividends on basis of fat and casein.
' — The same process is followed as before, except
that the yield of fat and casein, taken together, con-
stitutes the basis of division. The percentages of
fat and of casein in milk are added together, in each
case, and the sum multiplied by the number of
pounds of milk furnished, thus giving the number
of pounds of fat and casein furnished by each patron.
The total amount of fat and casein furnished by all
the patrons for the dividend period (279.36 pounds)
is divided into the net proceeds from the sale of cheese
and the result is the net dividend value (16.3 cents)
of one pound of mixed fat and casein. This figure
is then multiplied by the amount of fat and casein
furnished by each patron. The details are indicated
below.

Name

of
patron

Pounds
of milk

delivered
during

dividend
period

Per cent of

fat and

casein

in milk

Pounds of
fat and
casein

furnished

Amount

Net

of divi-
dend
due
each

price
received

for
cheese

patron

per
pound

Net

price

received

for fat

per
pound

A...
B...
C...
D..
E...

350
650
835
965
1200

x(4.0x2.50=)6.50
X(3.6X2.34=)5.94
x(5.2x2.98=)8.18
X(4.4X2.68=)7.08
X(4.2X2.58=)6.78

Cents

= 22.75x16.3

= $3.71

10.00

= 38.61X16.3

= 6.29

10.00

= 68.30x16.3

= 11.13

10.00

= 68.32X16.3

= 11.14

10.00

= 81.38x16.3

= 13.26

10.00

Cents
26.5
26.8
25.6
26.2
26.3

CHAPTER XXII

The Relations of Micro-Organisms and
Enzyms to Cheese-Making

Milk, on standing under ordinary conditions, under-
goes a variety of changes sooner or later, many of
which destroy its value for cheese-making purposes.
The most common and extensive changes occurring
in milk are due to fermentations. One result of some
kinds of fermentation is the production of bad flavors,
but these may be acquired also by direct absorption
from the surrounding air or from the food consumed
(p. 6). We shall see that certain kinds of fermenta-
tions are useful and necessary in cheese-making, while
others make it difficult or impossible to prepare a good
product.

FERMENTATIONS AND FERMENTS

The souring of milk is one of the most familiar
cases of fermentation. The important change taking
place is the formation of lactic acid from milk-sugar
and the change is caused by certain living organisms.
An equally familiar case of fermentation is the
coagulation of milk by rennet-extract. In this case
the change is produced, not by a living organism, but
by a chemical substance. That which causes fermenta-
tion is called a ferment.

Fermentation may be defined as a chemical change
of an organic compound through the action of living

286 SCIENCE AND PRACTICE OF CHEESE-MAKING

organisms or of chemical agents. We thus have two
general kinds of ferments, (i) organized ferments
and (2) unorganized ferments, known also as chem-
ical ferments or enzyms. In the illustrations given
above, the ferments are ( i ) lactic acid organisms and
(2) rennet ferment; in one case the organic matter
ohanged is milk-sugar; in the other, milk-casein.
Organized ferments are living micro-organisms,
capable, as a result of their growth, of causing fer-
mentations. Unorganized ferments are chemical sub-
stances, or ferments without life, capable of causing
marked changes in many complex organic compounds,
the enzyms themselves undergoing little or no change.

General characteristics of ferments. — Ferments
possess certain general characteristics in common,
among which may be mentioned the following: (i)
A very small amount of ferment is capable of pro-
ducing very great changes. (2) They are all de-
pendent upon temperature as a condition of activity.
They cease to act at low and also at high tempera-
tures. Most of them find the temperature that is
best suited to» their greatest activity between 80° and
100° F. (3) Ferments are destroyed by heat, the
temperature of boiling water, in most cases, com-
pletely destroying their power to act. Their activity
is checked by low temperatures, but, when again
warmed, they renew their activity. (4) The action
of ferments is checked or prevented by many sub-
stances. (5) When the products formed by ferments
accumulate in certain amounts, the ferment action
usually stops. (6) All ferments are closely con-
nected with living processes.

Organized ferments, or living micro-organisms
capable of causing fermentations, are divided into

MICRO-ORGANISMS AND ENZYMS

287

several classes; but those of greatest interest in con-
nection with cheddar cheese-making are called bac-
teria. These are the smallest conceivable forms of
plant life. Each individual consists of a single cell,
averaging in diameter one-thirty-thousandth of an
inch.

(i) Kinds. — Bacteria appear in three general
varieties of form: (a) Ball (coccus), (b) short rod
(bacillus), and (c) corkscrew (spirillum). (Figs.
39-42.)

FIG. 39 — BALL-SHAPED BAC-
TERIA (coccus).

(Rogers)

FIG. 40 — CHAINS OF BALL-
SHAPED (coccus) BAC-
TERIA

(Rogers)

(2) Method of grozvth and reproduction. — They
multiply in number, or reproduce, by simple division ;
that is, when a cell grows in size, it increases more
in one direction, so as to result in lengthening out
slightly, and a partition forms across the cell, thus
producing two new cells in place of the old one ; and
then each of these subdivides again and so on con-
tinuously. Some kinds of bacteria form spores in
the cells; these are to bacteria what seeds are to

2S^ SCIENCE AND PRACTICE OF CHEESE-MAKING

higher plants. Spores are not so easily killed by heat
as are bacteria. Under favorable conditions, the
rapidity of growth of bacteria is remarkable. Thus,
in some cases, one cell divides into two cells in 20
minutes; if this rate were kept up for 24 hours, the
one cell would multiply into several millions.

(3) Food requirements of bacteria. — Bacteria re-
quire as food for satisfactory growth compounds con-
taining nitrogen, carbon, hydrogen and, in addition,

FIG. 41 — ROD-SHAPED BAC-
TERIA (bacillus). CLEAR
AREAS IN SOME ARE

SPORES. (Rogers)

FIG. 42 — B A C T E R I A WITH
HAIR-LIKE ORGANS, WHICH
THEY USE IN MOVING
THEMSELVES ABOUT IN

LIQUIDS (Rogers)

small amounts of inorganic or mineral matter. The
sugar, casein, albumin and salts in milk and its
products furnish a supply of food very readily
utilized by bacteria.

(4) Temperature. — The bacteria commonly pres-
ent in milk grow between the limits of 40° and 110°
F., the miost favorable limits being between 80° and
95° F. Many bacteria are killed between 130° and

MICRO-ORGANISMS AND ENZYMS 289

140° F., when exposed to this heat for ten minutes,
and most of them are destroyed at 185° F. Many-
spores are killed at temperatures only above 212°
F., and even then require heating one to three hours.
(Fig. 43.) Dry heat is less effective than moist heat.
Live steam, therefore, affords a most effective means
of destroying bacteria. All bacteria are rendered in-
active at low temperatures and some may be killed
by intense cold. Many bacteria may retain life on
being dried and become active again when placed
under favorable conditions of moisture and tem-
perature.

(5) Action of sunlight, chemicals, etc. — Sunlight
kills many bacteria when they are exposed directly
to the sun's rays for a few hours. Bacteria are either
checked in growth or killed by many different chem-
ical compounds. Those compounds that simply
retard the rapidity of growth of bacteria are called
antiseptics, among which are carbolic acid, salt, salt-
peter, etc. ; those that destroy bacterial life are called
disinfectants, among which are mercuric chlorid (cor-
rosive sublimate), formaidehyd (formalin), potas-
sium bichromate, chloroform, etc. The activity of
each kind of bacteria is stopped by an accumulation
of products formed by it and, in some cases, by the
products of activity of other bacteria. Thus, most
kinds of lactic acid bacteria stop growing when about
0.9 per cent acid is formed, and much less than this
amount of lactic acid also prevents the growth of
many other bacteria.

(6) Changes produced. — In the course of their
growth, bacteria produce great changes in the
materials in which they grow; and the process by
which these changes are brought about are known,

290 SCIENCE AND PRACTICE OF CHEESE-MAKING

WATEB BOILS 2!2.

BLOOD HEAT—.

WATER FREEZES 32— =

—

ALL GROWING BACTERIA
— KILLED^

-GROWTH CEASES.

?-GROWTH MOST RARD.

-GROWTH RCTARDEO.

— JSROWTH CEASES.

FIG. 43 — INFLUENCE OF TEMPERATURE ON BACTERIA ORDINARILY

FOUND IN MILK (Rogers).

MICRO-ORGANISMS AND ENZYMS 29I

as previously stated, under the general name of fer-
mentation.

(7) Distribution. — Bacteria are found distributed
nearly everywhere in the soil, in the air and in water.
They are always present in large numbers wherever
vegetable or animal matter is undergoing decay. They
are, therefore, always closely associated with dirt and
filth. While some are the causes of dreaded diseases
and of serious troubles in cheese-making, most of
them are either harmless or actively helpful in many
ways.

Unorganized ferments or enzyms. — Many enzyms
are produced directly by bacteria and are the direct
agents producing the observed changes of bacterial
activity, while many are formed in higher plants and
in animals. Thus, the pepsin found in the human
stomach is an enzym; its special power or form of
activity enables it to change protein compounds from
insoluble to soluble forms. The ptyalin contained in
saliva is another enzym and is capable of changing
starch into sugar. Enzyms are destroyed by high
temperatures and by many disinfectants. Some sub-
stances, like ether, chloroform and formaldehyd, do
not seriously interfere with the activity of enzyms,
while they do destroy bacteria.

In connection with the subject of ferments, we
shall consider the following ones as those of most
importance in connection with cheese-making: (i)
Lactic acid bacteria, (2) gas-producing bacteria, (3)
digesting bacteria, (4) bacteria producing undesir-
able flavors, (5) yeasts, (6) milk-enzyms, (7) rennet-
enzyms, and (8) pepsin. The ferments that are

292 SCIENCE AND PRACTICE OF CHEESE-MAKING

responsible for many of the defects found in Amer-
ican cheddar cheese will be discussed only briefly here,
because their relations to cheese-making are fully
treated from a practical standpoint in Part II, pp.
I 15-130.

LACTIC ACID FERMENTATION

The ordinary souring of milk is due to the forma-
tion of lactic acid, which is produced by the action
of lactic acid bacteria (Bacillus lactici acidi. Fig. 44)
upon the sugar in milk. A large number of different

kinds or types of bacteria
are able to produce lactic
acid from milk-sugar.
Some interesting work
has been done recently
(Bull. No. 42, Mich.
Agr. Coll. Exp. Sta.)
which shows that other
micro-organisms are often
associated with the micro-
organisms of lactic fermen-
tation and that these

FIG. 44 — TYPICAL LACTIC-
ACID BACTERIA (Rogers)

micro-organisms

associate

often have the power of furnishing products that
exert a decided influence upon the rapidity of the
growth of the lactic micro-organisms.

We have already (p. 150) called attention to
the fact that the sour taste of milk is not due to the
presence of uncombined lactic acid, since little or no
free lactic acid is present in sour milk until it has
quite a high degree of acidity ; but is due to acid phos-
phate of calcium, which is formed by the action of
lactic acid upon the insoluble -calcium compounds in

MICRO-ORGANISMS AND ENZYMS 293

the milk. Milk begins to taste sour when its acidity
amounts to about 0.3 per cent ; which really means
when a little over 0.2 per cent of lactic acid has been
formed from milk-sugar; because the milk-casein
itself and the soluble phosphates have an acidity of
nearly o.io per cent (p. 153) when the milk is
freshly drawn and no milk-sugar has had a chance
to be changed into lactic acid. According to recent
work done at the New York experiment station,
milk curdles on boiling when the acidity reaches
0.32 to 0.46 per cent, and at ordinary room tempera-
ture when it reaches 0.58 to 0.72 per cent. When
artificial lactic acid is added directly to fresh milk,
curdling takes place on boiling when the acidity
reaches 0.36 per cent and at room temperature when
the acidity reaches 0.57 per cent. Bacteria continue
actively converting milk-sugar into lactic acid,
until the amount of acid reaches 0.8 to i.o per cent
of the milk; and then they greatly diminish or cease
their activity, because they cannot thrive in a solu-
tion showing this amount of acidity. Their activity
is thus stopped by the accumulation of the chief
product of their own activity, and not because the
supply of milk-sugar runs out; for, when their
activity ceases, about three-quarters of the milk-
sugar remains still unconsumed. Products besides
lactic acid are formed, varying according to tem-
perature and other conditions. In recent work at
the New York experiment station, we have ob-
tained, in the form of lactic acid, about 80 per cent
of the milk-sugar that was decomposed. In connec-
tion with cheese-making, the total acidity of the whey
may rise as high as 1.2 per cent. Under conditions,
which are not present in cheddar cheese-making,
some micro-organisms may produce as much as 3

294 SCIENCE AND PRACTICE OF CHEESE-MAKING

per cent of lactic acid, decomposing a correspond-
ing amount of milk-sugar.

The range of temperature most favorable to lactic
acid organisms is 90° to 95° F. Below 80° F. their
activity gradually decreases and practically ceases at
50° F. At 105° F., they are fairly inactive; many
are killed at 135° to 140° F., and all at 150° to
160° F.

While the lactic acid fermentation spoils milk for
the taste of most people, at least for ordinary uses, it
is a very essential factor in the manufacture of cheese.
Very few lactic acid bacteria are found in fresh milk,
but they increase so rapidly at ordinary temperature
(70° F.) that in 12 to 18 hours they generally exceed
in number all other bacteria in milk. In summer
weather, when the temperature is especially favorable
to their rapid growth, the lactic acid bacteria usually
constitute, at the time the milk sours, more than 95
per cent of all the micro-organisms in the milk.

While the growth of lactic acid organisms in milk
is favored by the presence of a small amount of acid,
most other organisms do not thrive so well in an acid
environment. Therefore, as soon as enough milk-
sugar has been converted into lactic acid to produce
a slightly acid condition, other organisms decrease
in activity, while the lactic acid organisms vigorously
increase, unhindered. It is quite commonly thought
that milk is peculiarly liable to sour during thunder-
storms, as the result of some peculiar electrical con-
dition or other mysterious influence. The hot weather
preceding such storms favors the more rapid growth
of the lactic acid bacteria and this is a sufficient ex-
planation, and the proper one. Milk free from such
micro-organisms never sours during thunderstorms.

MICRO-ORGANISMS AND ENZYMS 295

The lactic acid fermentation we have been con
sidering is what we may call the normal form, the
particular form we desire to have present in milk in
cheese-making. Their presence is insured by the use
of good starters (p. i8). Milk in which this form
of lactic fermentation has occurred produces, in
souring, a firm curd free from gas bubbles and with
only a little whey on the surface. When agitated,
the curd breaks apart readily into small particles,
which settle slowly and leave a clear whey. The
milk should have a pleasant, clean, acid taste, en-
tirely free from anything resembling a tainted flavor.
So far as we know, the lactic acid bacteria belonging
to this normal group never form products of a poison-
ous character.

GAS-PRODUCING BACTERIA

Some of the bacteria that decompose milk-sugar
with formation of lactic acid are usually grouped with
the lactic acid bacteria, though they possess distinguish-
ing characteristics which mark them as abnormal, so
far as their behavior in cheese-making is concerned.
While they decompose milk-sugar and produce lactic
acid, they produce other products besides, especially
gases ; they may also produce volatile products that
are offensive. These bacteria are responsible for many
of the defects in cheese (pp. 116-130). When gas-
producing ferments are present in milk, they are
usually responsible for increased losses of fat in the
cheese-making process.

DIGESTING BACTERIA

A large group of bacteria curdle milk without sour-
ing it and then slowly digest or dissolve the curd;

296 SCIENCE AND PRACTICE OF CHEESE-MAKING

therefore, they are often called "liquefiers." These
effects are due to enzyms which are produced by the
bacteria. Some of these bacteria form products that
are offensive in flavor ; some produce gases, and some,
acid. They may be a source of serious trouble in
cheese-making in the production of gassy curd and
offensive flavors in cheese. They may also cause
some dissolving of the curd, in which case the loss of
fat is unusually large. These bacteria are widely dis-
tributed, being found in stable filth, in soil, water and
floating dust. They are nearly always present to some
extent in milk. Fortunately, their activity is checked
by the presence of lactic acid, and the easiest method
of controlling such ferments in cheese-making is to
make conditions favorable for the rapid growth of
normal lactic acid bacteria ; this is usually accom-
plished by the use of a pure starter. The growth of
digesting bacteria in milk is favored by high tempera-
ture; consequently, in hot weather, when the high
temperature favors the growth of the digesting bac-
teria more than it does the lactic acid organisms, the
undesirable forms get beyond control and seriously
impair the operations and results of cheese-making.

BACTERIA PRODUCING UNDESIRABLE

FLAVORS

Different bacteria are responsible for rrtany different
kinds of bad flavors in milk and cheese, among which
are the following: Bitter (p. 119), fishy, rancid or
butyric acid, hydrogen sulphid (p. 116).

YEASTS

Yeasts are micro-organisms resembling bacteria in
some respects, but usually larger. The})- are very

MICRO-ORGANISMS AND ENZYMS 297

widely distributed and are common in milk. The con-
ditions usually present in milk are not favorable to
their growth and they are not, therefore, the source
of trouble so often as are bacteria. Among the effects
which can be attributed to the action of different
yeasts are the formation of bitter and of fruity flavors
(pp. 118, 126).

MILK-ENZYMS

Milk contains several different enzyms. Some of
them, at least, are of bacterial origin. It would take
us too far from the purpose of this discussion to go
into details relating to milk-enzyms. We shall con-
fine our attention to the one known as galactase. In
1897, Babcock and Russell announced the discovery
of an unorganized ferment or enzym in milk to which
they gave the name of galactase. They were led to
this discovery by observing that fresh milk coagu-
lates, even when obtained as free as possible from
bacteria, and when all bacterial activity has been
stopped by treatment with ether or chloroform. The
milk first coagulates and then the curd gradually dis-
solves. Having excluded the seeming possibility of
bacterial action in the milk after it was drawn, they
concluded that the observed coagulating and dissolv-
ing action must be due to enzym action, probably two
different enzyms. Galactase is probably a mixture
of two or more different enzyms, since it has
been shown that separator-slime, when treated accord-
ing to Babcock and Russell's method in preparing
galactase contains at least three distinct enzyms,
galactase proper, peroxidase and catalase. The dis-
tinctive feature of the action of galactase is its powei

298 SCIENCE AND PRACTICE OF CHEESE-MAKING

to change insoluble proteins like milk-casein into
soluble forms.

The following have been given as some of the more
prominent characteristics of galactase. ( i ) Galac-
tase readily attaches itself to finely divided particles
in suspension like milk-casein and fat-globules ; hence,
it is found in separator-slime and in cream to a greater
extent than in milk or skim-milk. (2) The most
favorable temperature for the action of galactase lies
between 98° and 108° F. Heated for ten minutes
above 168° F., its activity is destroyed, as shown by
the following table : - '

EFFECT OF HEAT ON GALACTASE IN MILK

Temperature used
in heating milks

Age of milks

when

analyzed

Soluble nitrogen expressed

in percentage of nitrogen

in milk

Degrees
90°C.(194°F.)
85°C.(185°F.)
85°C.(185°F.)
95°C.(203°F.)
95°C.(203°F.)
98°C.(208°F.)

Months
13
8
7
IS
16
14

Per cent
4.26

10.8
9.7
5.52
5. 5

11.5

(3) Free acids, especially hydrochloric acid, retard
the activity of galactase. Neutral or alkaline reac-
tions favor its action. (4) Many disinfectants, like
mercuric chlorid, carbolic acid, formaldehyd, carbon
disulphid, etc., retard or prevent the action of galac-
tase. (5) Its activity is greater in the early stage
of working, as measured by the rapidity with which
casein is -changed into soluble compounds.

As a result of their work, Babcock and Russell
concluded that galactase is a trypsin-like ferment,

MICRO-ORGANISMS AND ENZYMS 299

except that one of its most distinctive characteris-
tics is its abihty to form, among other products,
ammonia, and that, therefore, galactase plays a
principal role in cheese-ripening. Their galactase
work has been confirmed to the extent that there is
in milk some enzym that causes more or less de-
composition of milk-casein and of cheese paracasein
in the presence of chloroform or ether. In work
done at the New York experiment station, the ability
of galactase to form ammonia was not confirmed
either in case of milk or cheese. Cheese kept in an
atmosphere of chloroform produced no ammonia or,
at most, only slight traces even at the end of 15
to 24 months. Samples of the cheese were sent to
the Wisconsin experiment station, and the absence of
ammonia was there confirmed. The view previously
held to the efifect that galactase was able to account
for most of the changes in cheese-ripening was then
modified.

RENNET-ENZYMS

Rennet-extract contains one or two unorganized
ferments or enzyms. There has long been a differ-
ence of opinion as to whether there is in rennet-extract
one enzym which acts in two different ways or two
different enzyms„ each with its own characteristic
action. So far as the essential facts are concerned,
rennet-extracts possess the power of effecting two
distinct kinds of changes : ( i ) coagulation of milk-
casein and (2) dissolving or digesting the milk-casein
coagulum. Those who regard these two actions as
due to two different enzyms contained in rennet call
the coagulating enzym rennin or chymosin, and the

300 SCIENCE AND PRACTICE OF CHEESE-MAKING

dissolving enzym, pepsin. The best evidence at hand
at present rather favors the existence of two enzyms.
For our purpose, it is immaterial whether there is one
enzym or more. Our chief interest in rennet, in con-
nection with the cheese-making process, lies in its
characteristic property of coagulating milk-casein.
Whether the dissolving action of rennet-enzym plays
any part in the operation of cheese-making, we do
not know at present. We do know, however, that it
has some action in the cheese-ripening process (p.
362).

Source of rennet-enzym. — The rennet-extract
used in cheese-makmg is a dilute and impure form ot
rennet-enzym. ' The usual source of rennet-extract is
the fourth stomach of a suckling calf. It is also pre-
pared in more concentrated condition in the form of
powders and of tablets. Enzyms having the same
action as that of rennet are found also in plants and
in other animals than calves. Some bacteria pro-
duce a coagulating enzym like that in rennet.

Home-made rennet-extract. — Formerly, cheese-
makers purchased rennets from farmers and prepared
the extract from time to time as needed. The stomach
of a freshly slaughtered calf was cleaned, salted and
dried by farmers and sold to the cheese-maker. In
preparing the home-made extract, a number of ren-
nets are cut in pieces and just covered with salt brine
in a suitable vessel, about 3 or 4 pounds of salt
being added to 100 pounds of water. The mix-
ture is vigorously stirred and pounded. Once a week
the rennets are removed from the brine and passed
through a press or clothes-wringer and then placed
in the brine again. It requires about four weeks to

MICRO-ORGANISMS AND ENZYMS 3OI

complete the extraction. The sohition thus obtained
is filtered through clean straw, sand, and charcoal and
then treated with enough salt to prevent decomposi-
tion; a brine containing 6 or 7 pounds of salt to lOO
pounds of solution is about the proper strength.
Rennet-extract properly prepared is dark in color, but
clear. The appearance of turbidity in the extract is
an indication of the beginning of decomposition. It
must be kept in a cool, dark place. In some cases,
whey was once used as a medium for preparing ren-
net-extract, a practice that would insure a large num-
ber of objectionable micro-organisms in the extract.
It can readily be seen how home-made rennet-extract
may be a source of serious bacterial contamination
in milk. The preparation of home-made extracts is^
fortunately, much less common now. The serious
objections to their use are (i) liability to bacterial
contamination and (2) variation in strength of dif-
ferent lots, usually requiring the use of quite variable
amounts of one preparation as compared with another.

Commercial rennet-extract. — The general substi-
tution of commercial for home-made rennet-extracts
is of distinct advantage in cheese-making, because the
commercial forms are much more uniform in strength
and less liable to bacterial contamination. Commer-
cial rennet-extracts contain about 16 per cent of salt
and a trace of boric acid. Some have expressed the
fear that the boric acid used as a preservative in ren-
net-extract might injure the value of cheese as a pure
food. There need be absolutely no alarm felt, when
we consider the small amount of rennet-extract used
in cheese-making and the very small proportion of
this that goes into cheese. In fact, the amount of

^02 SCIENCE AND PRACTICE OF CHEESE-MAKING

boric acid introduced into cheese through the rennet-
extract is too small to identify by delicate chemical
tests. Commercial rennet-extracts vary in strength
and new lots always need testing before being used

(P-430).

Strength of rennet-enzym in coagulating milk-
casein. — How powerful the action of rennet-enzym
is in coagulating milk-casein can be seen in cheese-
making, where we use only about one part of rennet-
extract for 4,000 or 5,000 parts of milk, and it must
be kept in mind that rennet-extract is only a dilute
form of the rennet-enzym. It has been estimated that
one part of pure rennet-enzym can coagulate three
million parts of milk. Apparently, rennet-extract
does not exhaust itself by its own action, a general
characteristic of enzyms, but can be repeatedly used;
at least this is theoretically true. For example, if we
could recover from whey and curd the rennet used
in coagulating milk, it would coagulate an equal quan-
tity again. As stated already, one of the most char-
acteristic properties of an enzym is that it can produce
very powerful effects without itself being affected in
any way.

Explanation of the coagulating action of rennet-
enzym. — A large amount of effort has been devoted
to the study of the coagulating effect of rennet-enzym
in order to asfcertain just what the rennet does to the
milk-casein to make it coagulate. Many different ex-
planations have been offered, but in the present state
of our knowledge it is impossible to give an explana-
tion of the process that can be regarded as satisfac-
tory and conclusive. The most we can do here to
advantage is to present the details of the process, so

MICRO-ORGANISMS AND ENZYMS 303

far as they appear to be worked out. The rennet
coagulation of milk-casein is believed to take place
in three quite distinct stages or phases, as follows :
(i) Change of casein into paracasein; (2) change
of the calcium salts of the milk into soluble form ;
and (3) precipitation of uncoagulated paracasein by
the soluble calcium salts.

(i) First stage of rennet action; change of casein
into paracasein. — The change of casein into paracasein
is wholly dependent on the action of rennet-enzym.
There is no change visible to the eye, neither increase
of consistency (viscosity) nor any apparent coaguk-
tion. In the absence of soluble calcium salts, the
paracasein that has been formed remains in this un-
coagulated condition. The action in this stage of the
process takes place as well in the cold as at higher
temperatures. What evidence have we that casein is
changed into paracasein before coagulation takes
place ? This is shown experimentally as follows : To
a solution containing some salt of casein, free from
soluble calcium salts, we add rennet-extract. No co-
agulation takes place. This solution is heated high
enough to destroy the power of the rennet to a.ct and
then cooled, after which calcium chlorid or some other
soluble calcium salt is added, when coagulation ap-
* pears at once. It may be stated here that one of the
/ most characteristic differences between milk-casein
and paracasein is that soluble calcium salts da not
coagulate milk-casein at ordinary temperatures, but
they do cause coagulation of paracasein. In the fore-
going experiment, rennet does something to the casein
compound which causes the casein* to do what it could
not do before, that is, coagulate at ordinary tem-
peratures by addition of soluble calcium salts, even

304 SCIENCE AND PRACTICE OF CHEESE-MAKING

when the rennet-enzym itself had been removed
from the field of action.

(2) Second stage of rennet action; change in
calcium salts of milk. — In the second stage of rennet
action, it is believed that the rennet-enzym acts upon
the insoluble calcium salts of the milk, converting
them into a form sufficiently soluble to enable them to
coagulate the paracasein. This action appears to take
place more slowly than does the conversion of casein
into paracasein. This accounts for the period of time
that elapses between addition of rennet and coagula-
tion ; this time can be shortened by addition of soluble
calcium salts.

(3) Third stage of rennet action; precipitation of
uncoagiilated paracasein. — During this period, in-
creased viscosity (thickening) and visible coagulation
take place. This change, it is generally agreed, is
caused by the action, either physical or chemical, of
soluble calcium salts upon the uncoagulated paracasein
formed during the first stage of the process. After
the second stage is completed or nearly so, coagulation
commences and proceeds rapidly. The paracasein
coagulum (curd) formed in milk always contains in-
soluble calcium phosphate, which is probably held in
a purely mechanical way, although some believe that
it is in combination with paracasein.

What is the evidence leading us to believe that a
soluble calcium salt is necessary for the coagulation of
milk-casein ? Two lines of experimental evidence have
been furnished, (ist) If we prepare a pure solution
of neutral calcium casein or sodium casein, contain-
ing no soluble calcium salts, rennet-extract will not
coagulate such a solution, but, after the addition of
some soluble calcium salt, as calcium chlorid, coagula-
tion takes place promptly. (2nd) Milk from which

MICRO-ORGANISMS AXD £NZYMS 305

the soluble calcium salts have been removed by pre-
cipitation with ammonium oxalate or by dialysis is
not coagulated by rennet-enzym until a soluble cal-
cium salt is added. We may, therefore, summarize
as follows what appears to be fairly well established
in explanation of the coagulating action of rennet :
(i) That milk-casein is the only substance in milk
involved in the rennet coagulation, excepting phos-
phates of calcium and other soluble salts of calcium.
(2) That in rennet coagulation, no change of reaction
or acidity occurs; the milk becomes neither acid nor
alkaline through rennet action. (3) That the two
active agents in the rennet coagulation of milk are
rennet-enzym and soluble calcium salts.

Relation of casein and paracasein. — In the fore-
going discussion of the process of rennet coagula-
tion, there is nothing to indicate just what happens
to milk-casein in being changed into paracasein,
or, in other words, just how paracasein really dif-
fers from milk-casein. It must be confessed that
we do not know at all clearly, although there are
many suggestions. We know only this with cer-
tainty, that milk-casein does not readily coagulate
in the presence of dilute calcium salts at ordinary
temperatures, but paracasein does. Otherwise the
general properties of casein and paracasein are
very similar. Some hold that the difference is
purely physical, the paracasein consisting of larger
particles than the casein. While the ultramicro-
scopic study (p. 143) of rennet coagulation enabled
the observers to see the minute particles of casein
come together and form larger aggregations under the
action of rennet, this does not show whether this

306 SCIENCE AND PRACTICE OF CHEESE-MAKING

physical change was accompanied by any chemical
change in the milk-casein.

Dissolving or digesting action of rennet-enzym. —

Rennet-extract has the power of dissolving paracasein,
this peptic action being slow but continuing for a long
time in cheese. Whether one enzym does both the
coagulating and the digesting, or whether there are
two specific enzyms (rennin and pepsin), each per-
forming its special kind of work, is not fully settled,
but, as already stated, the results of most recent in-
vestigations point to two distinct enzyms.

Conditions of action of rennet-enzym. — The con-
ditions under which rennet-enzym coagulates milk-
casein have been extensively studied and we will now
consider some of the more important ones. The
rapidity and completeness of coagulation of milk-
casein by rennet-enzym are dependent upon the fol-
lowing conditions :

(i) The presence of soluble calcium salts appears
to be necessary for the coagulation of milk-casein by
rennet-enzym. This has been discussed already.

(2) Effect of acids. — Milk must be neutral or acid
in reaction in order to be coagulated by rennet-enzym.
Free acids or acid salts favor the action. All acids,
whether organic or inorganic, show very marked effect
upon the coagulation, though they differ from one
another in respect to the extent of influence which
they exert on rennet action. The more acid there is
in the milk, up to a certain limit, the more quickly does
coagulation by rennet-enzym take place. Milk sour
enough to curdle is not coagulated by rennet; sim-
ilarly, sour buttermilk is not coagulated. The follow-
ing table shows the results of some work done at the

MICRO-ORGANISMS AND ENZYMS

Zoy

New York experiment station on this subject. The
experiments were made by treating 350 cubic centi-
meters of fresh milk at 84° F. with i.o cubic
centimeter of rennet solution, made by dissolving one
of Hansen's rennet-tablets in 150 cubic centimeters of
distilled water.

Original

milk

coagulated

seconds

Strength of acid used

Acids used

0.01
per cent

0.02
per cent

0.03
per cent

0.04
per cent

0.05
per cent

Time of coagulation

in seconds

'/v^ C '-<.-> /-f Acetic

AS S^'i Sulphuric

* Citric

110
105
105
110
105
135

70
70
80
80
85
110

45
50
60
65
70
90

35
30
45
45
60
80

25
25
40
35
50
75

20
35

-f^^/*'<'^^/V Lactic

r >v<:^ Hydrochloric .
^j ^<^y^ Phosphoric . .

30
45
60

This effect of acids upon rennet action is com-
monly explained by saying that the added acid dis-
solves the insoluble calcium phosphates of milk and
thus increases the amount of soluble calcium salts.
It is known that even carbon dioxid gas favors rennet
coagulation, due to its dissolving action on insoluble
calcium salts in milk.

(3) Dilution of milk by water both delays rennet
action and renders coagulation less^ complete, because
the proportion of soluble calcium salts is decreased.
Addition of calcium chlorid or free acid to milk thus
diluted not only hastens the time of coagulation, but
makes more complete the amount of milk-casein co-
agulated. Apparently, milk may be diluted more than
10 per cent with water before the time of rennet

308 SCIENCE AND PRACTICE OF CHEESE-MAKING

coagulation Is greatly affected. The effect of water
is illustrated in the following table :

Cubic

Cubic centi-

Percentage of

Cubic centi-

centimeters

meters of

added water

meters of

Time of

of milk

water added

in watered

rennet solu-

coagulation

to milk

milk

tion used

Minutes-Seconds

175

0.5

5 — 20

175

1.0

3 — 20

280

1.0

2-00

315

1.0

1 — 50

332i

I7i

1.0

1 — 45

350

1.0

1 — 30

(4) Different chemical compomids and metals
affect the rennet coagulation of milk in different ways.
Acid salts, in general, like free acids, favor rapidity
of coagulation. Alkalis and alkaline salts retard it.
The following substances, if present in certain
amounts, retard rennet coagulation of milk-casein :
Sodium chlorid (common salt), sodium acetate,
borax, chloroform, formalin and some other sub-

Origi-
nal
milk

Strength of Compound Used

Compound
used

0.01
per cent

0.05
per cent

0.10
per cent

0.5
per cent

1.0
per cent

2.0
per cent

Number of seconds required to coagulate milk

Sodium chlorid
Sodium nitrate
Sodium bicar-
bonate

Sodium acetate
Borax ........

Boracic acid.. .
Ammonium

chlorid

Ammonium
carbonate. . .

Lime-water . . .

110

115
115
100
100

135

115
120
120
100 '

140

150

170
180
270
100

130

195

265

280

600

130

300

115

(lOcc.)
150

120
ISO

(20cc.)
165

160
225

(30cc.)
210

MICRO-ORGANISMS AND ENZYMS

309

stances, which are used in milk as preservatives. The
foregoing table shows the results of some work done
at the New York experiment station on this point.

It has been shown at the Wisconsin experiment
station that some metals exert a retarding effect on the
coagulating action of rennet. As a practical applica-
tion, it is pointed out that in rusty milk-cans enough
iron may be dissolved by milk that is at all acid to
interfere with the rennet coagulation.

(5) Finely divided, inert matter, like starch or
sawdust, added to milk, hastens the coagulation by
rennet.

(6) The temperature of the milk affects (i) the
time of coagulation, and (2) the character of the
curd.

(a) For complete coagulation, the time de-
creases when the temperature increases.

Temperature, F.
Time, seconds. . .

75°
270

80°
140

85°
110

90°
80

95°
65

Stated in another way, the coagulation in a given
time is most complete at 106° to 108° F. and less
complete at temperatures above and below these
limits. Fleischmann gives the following figures,
indicating the proportion of milk-casein coagulated in
the same period of time required to effect complete
coagulation at 106° to 108° F.

Proportion of milk-
Temperature casein coagulated

68° ; 18 per cent

77° 44 per cent

86° 71 per cent

95° 86 percent

104° 98 per cent

106°. 100 per cent

113° 89 per cent

122° SO per cent

3IO SCIENCE AND PRACTICE OF CHEESE-MAKING

(b) The character of the coagulation is af-
fected by the temperature at which the rennet-
enzym acts. Thus, at 60° F., the curd is flocculent,
spongy and soft; at yy° to 113° F., it is more or less
firm and solid; at 122° and above, it is very soft, loose
and inclined to be gelatinous.

(c) Milk heated above 150° F. for a consider-
able length of time coagulates less rapidly than nor-
mal milk. The coagulum of such heated milk is
highly flocculent, never a firm and solid mass, in the
absence of soluble calcium salts or acids. Boiled
milk fails" to coagulate normally, if at all, by rennet-
enzym, unless treated with some soluble calcium salt
or some acid. The degree of heat used decreases the
amount of soluble calcium salts in milk and also drives
out any carbon dioxid present.

<» (7) Exposure to sunlight weakens the coagulating
' power of rennet-extract.

(8) Solutions of rennet-extract are affected by
heat. — Rennet-extract heated for some time above
140° F. becomes permanently weaker, or inactive.
Rennet-enzym begins to suffer injury at about 120° F.
Weak solutions are injuriously affected at tempera-
tures as low as 105° F. Strong solutions are weak-
ened by heating at 150° F. for 15 minutes, but are not
entirely destroyed. High temperatures destroy the
activity of rennet-enzym gradually, not instantane-
ously.

(9) Increase in amount of rennet-extract or in
strength of rennet-enzym hastens coagulating effect on
milk.

(10) Milk, freshly drazvn, curdles more com-
pletely than when allowed to cool, due to lowering of
temperature and, perhaps, to the presence of more

MICRO-ORGANISMS AND ENZYMS

311

carbon dioxid. In freshly drawn milk, the proportion
of casein coagulated decreases until the temperature of
the surrounding air is reached, when it becomes sta-
tionary, until the formation of lactic acid causes in-
crease in activity of rennet-enzym. When fresh milk
fails to coagulate with rennet-extract, it is probably
slightly alkaline or contains no soluble calcium salts ;
that is, it is abnormal.

(11) Different milks behave differently toward
rennet-enzym. This is true not only of milk from dif-
ferent cows, but also of milk from the same cow at
different times. The following results of work done
at the New York experiment station illustrate this
statement :

Time of coagulation and date of testing

Number
of cow

July 9

July 16

July 21 Aug. 10

Aug. 21

Sept. 15

Sept. 25

Oct. 30

2
3
4
5
6
7
8
9

10
11
12
13
14
15
16
17

M.— S.

M.S.

M.— S.

6—15

5—00

5—20

4—20

6-45

8—30

7—00

3—45

4—20

3—40

3—30

5-00

2—15

2—50

3—00

2—45

2-00

2—50

2—30

2—25

1—50

3—30.

2—10

2—15

2—05

2-00

1—25

2—00

2-00

2—05

2—50

2—45

2—40

2—05

1—55

2—00

2—05

1—55

1—50

1—55

2—00

1—50

2—10

2—30

4—001

4—15

4 — 20

3-00

2—40

3—30

3—00

3—45

1—35

1—50

2—10

1—45

1—25

1—40

1-45

1—35

1—40

2—10

2-00

2—20

1—50

1-55

1—45

2—30

1—05

1—10

1—05

1—10

23—00

16—20

10—00

29-00

4 — 45

50 — 00

0—50

0 — 45

0—50

0—45

1-00

0—50

0—40

2-05

2—30

2-00

1—55

3—00

3-00

3—10

1—55

1—45

1—55

2—05

1—40

1—35

1—40

M.— S.
6-00
4—15
2—00

2—30
2—15
1—402
3 — 10
2-00

7—00
0—45

i— 30

* Close of lactation period. 2Fresh in milk.

These results show that in the individual milkings
of these 17 cows the time of rennet coagulation of
fresh milk varied from 40 seconds to 50 minutes. In

312 SCIENCE AND PRACTICE OF CHEESE-MAKING

the case of one individual (No. 14), the variations
were from 4 minutes and 45 seconds to 50 minutes.
A study of the ordinary composition of the milk gave
no clue to the cause of such differences. The specific
causes are not yet understood, but are probably related
to the calcium salts in milk and their solubility.

PEPSIN-ENZYM

The chief enzym of the gastric juice in the stomach
of man is known as pepsin. The same enzym is also
present in the stomach of many animals. A prepara-
tion made from the stomachs of sheep is on the
market, which may be successfully used as a sub-
stitute for rennet-extract in cheese-making. This
has the property of both coagulating and digesting
milk-casein. The pepsin most experimented with
has been the scale pepsin of Armour & Co. This
pepsin does not coagulate very sweet milk as read-
ily as rennet-extract, but in milk having an acidity
of 0.20 per cent, it acts just as well, when used in
the proportion of 5 grams for 1,000 pounds of
milk. The pepsin is dissolved in any convenient
amount of water before addition to milk. The
solution should be prepared fresh for each day's use.
The complete identity of rennet-enzym and pepsin is
not fully settled. Assuming that the coagulating
effect of these preparations is due to one enzym
(rennin) and the digesting effect to another (pepsin),
the various preparations differ in respect to the
amounts of these two enzyms which they contain.
Rennet-extracts contain more rennin and less pepsin,
while the commercial preparations made from the
stomachs of pigs and sheep appear to contain more
pepsin and less rennin.

CHAPTER XXIII

The Ripening of Cheese

It is well known that chedclar cheese must have age
before it is edible. When taken from the press, cheese
is said to be unripe, green, or uncured. At this time,
it has no real cheese flavor, and little flavor of any
kind. Its body is very firm, somewhat tough, rather
elastic, and rubber-like. Its proteins are only slightly
soluble in water. It is not palatable and requires much
mastication before it can be swallowed comfortably.
Green cheese gradually undergoes very marked
changes in the course of some weeks or months, the
time required depending" upon a variety of conditions.
The cheese finally becomes mellow in body and ac-
quires richness of taste and a characteristic delicacy of
flavor. It is highly palatable and, when a piece is
held on the tongue a short time, the cheese dissolves,
giving a sensation of smoothness and richness. The
casein-derived proteins, which are insoluble as found
in the curd and green cheese, become soluble to a
large extent. The process, by which the qualities of
the newly made cheese are so profoundly changed
and as a result of which the product becomes edible,
is known as ripening or, less aptly, as curing.

For a long time the importance of caring for cheese
after it leaves the press was not appreciated, and not
until within about 15 years has much attention been
given to methods of cheese-ripening in this country.
The rule has been and still is, in too many cases, to

313

314 SCIENCE AND PRACTICE OF CHEESE-MAKING

place the cheese in some room in the factory where
are provided no means of controlHng temperature and
moisture and where the variations in these factors
closely follow, up and down, the conditions existing
out of doors. It has come to be realized that a cheese,
perfect when it leaves the press, may easily be ruined
for market by lack of care during the ripening process.
It is appreciated now more than ever before that the
ripening of cheese is a part of the manufacturing proc-
ess, that it is the" real finishing of the product, and
must not be slighted any more than any other impor-
tant step.

CHANGES RESULTING FROM RIPENING

PROCESS

Several different changes take place in cheese dur-
ing the ripening period. These may be divided into
two general classes, (i) loss of weight and (2)
chemical changes in the cheese constituents. We
shall now take up for consideration a somewhat de-
tailed study of (i) the extent to which these
changes take place, (2) the various conditions under
which they occur, (3) their relations to the character
of the cheese and (4) the commercial relations of
cheese-ripening.

LOSS OF WEIGHT IN CHEESE-RIPENING

The loss of weight in the cheese-ripening process,
when the conditions are normal, may be regarded for
practical purposes as being due entirely to the evapora-
tion of water from the cheese. Of course, there is
some mechanical lo^s of fat by exudation ("leak:ing")
from cheese kept at high temperatures, but such ccm-
ditions are abnormal. The small amount of loss due

RIPENING OF CHEESE 315

to the formation and escape of carbon dioxld (p.
334) and other gases can be neglected for practical
purposes.

CONDITIONS AFFECTING LOSS OF WATER
IN CHEESE-RIPENING

The rapidity and extent of loss of moisture in
cheese during the process of ripening vary with sev-
eral conditions, chief of which are the. following : ( i )
The temperature of the room, (2) the pro[>ortion of
water- vapor present in the air of the room, (3) protec-
tion of surface of cheese, (4) size and shape of the
cheese, (5) the percentage of moisture originally pres-
ent in the cheese, and (6) the texture of the cheese.
The data used in illustrating these points are taken
largely from the results of investigations carried on
at the New York experiment station.

Temperature and loss of weight. — We present,
first, data showing the influence of temperature upon
the loss of moisture at six different temperatures, viz :
55°, 60°, 6s°, 70°, 75° and 80° F.

The cheeses used in furnishing data in the table on

page 316 were 15 inches in diameter and weighed

about 65 pounds, the usual standard size of the most

common type of American cheddar cheese intended

t for export trade.

These results show an increase in loss of weight
with increase of temperature. As betweein 55° and
80° F., the loss increased on an average i ounce per
100 pounds of cheese for each additional degree of
temperature during the first 4 weeks ; 2 ounces per
100 pounds of cheese for each degree during the first
2 months ; and 3^ ounces at the end of 3 months.

3l6 SCIENCE AND PRACTICE OF CHEESE-MAKING

LOSS OF MOISTURE AT DIFFERENT TEMPERATURES

Tempera-
ture of
curing-
room

Water lost by 100 pounds of green cheese in

wk.

wks.

4
wks.

wks.

12
wks.

wks.

24
wks.

wks.

Degrees F.

Lbs.

1.6

2.6

3.2

3.7

5.2

6.1

6.8

7.5

8.1

1.7

2.8

3.4

3.9

5.5

6.5

7.5

8.5

9.3

1.9

3.0

3.6

4.1

5.8

7.0

8.2

9.2

10.1

2.0

3.1

3.7

4.3

6.0

7.8

9.0

10.1

11.1

2.2

3.3

4.0

4.7

7.2

9.7

11.4

2.4

3.7

4.5

5.2

8.3

11.6

15.5

Lbs.

8.6

9.9

10.5

12.0

The average weekly loss of weight increases with
increase of temperature. In the following table, it
is seen that the loss is greater the first week than in
any succeeding week. The loss usually decreases
gradually as the cheese grows older ; but cheese kept
at a temperature of 75° F. and above does not follow
this general rule, since at the higher temperatures
there is apt to be an increase of loss of weight due to
leakage of fat after the first month. This is shown
in the table below :

AVERAGE WEEKLY LOSS AT DIFFERENT TEMPERATURES

Average loss per week.

Temper-

Water lost by 100 pottnds of green

cheese.

lbs. total

ature of

loss for

curing-

six

room

1st

4th

5 th

6th

months

wk.

mo.

Deg. F.

Ozs.

Lbs.

25.6

16.0

9.6

8.0

6.0

3.6

2.8

2.4

8.1

27.2

17.6

9.6

8.0

6.4

4.0

3.2

9.3

30.4

17.6

9.6

8.0

6.8

4.8

4.0

3.6

10.1

32.0

17.6

9.6

6.8

4.8

4.4

4.0

11.1

35.2

17.6

10.2

10.0

6.8

38.4

20.8

12.8

10.2

12.4

13.2

15.6

RIPENING OF CHEESE

317

The comparatively rapid loss of moisture during
the early stage of ripening is due to the fact that the
cheese contains its highest amount of moisture when
new. In addition, the bandage is practically saturated
with water, which quickly evaporates. Then, again,
the outer surface of the cheese, in drying, begins to
harden, the meshes of the cheese-cloth filling to some
extent with dried matter, and this condition tends con-
stantly more and more to diminish evaporation, pro-
vided cracking is prevented.

Moisture in air of curing-room and loss of
weight. — The relative amount of moisture in air or,
more properly, the degree of saturation, exercises
a marked influence upon loss of water in cheese-ripen-
ing. To illustrate this influence, we give results of
an experiment in which two cheeses made from the
same milk were kept at 60° F. One cheese was kept
on a shelf in the ordinary manner, the air of the
room containing from 75 to 80 per cent of all the
moisture it could hold at 60° F. The other cheese

LOSS OF MOISTURE IN CHEESE KEPT IN AIR COM-
PLETELY AND PARTIALLY SATURATED WITH MOISTURE

Age of

In air partially saturated

In air completely satu-
rated with moisture

cheese

Moisture in
cheese

Water lost by

100 pounds of

cheese

Moisture in
cheese

Water gained

by 100 pounds

of cheese

2 weeks. . . .

1 month . . .

2 months. .
6 months. .

12 months. .
IS months. .

Per cent
35.99
35.23
34.86
31.87
26.30
24.85

Pounds

Per cent
35.93
35.87
36.01
37.04
37.63
37.85

Pounds

0.76.
1.13
4.12
9.69
11.14

0.08
0.11
1.70
1.92

3l8 SCIENCE AND PRACTICE OF CHEESE-MAKING

was placed un.cler a bell- jar and kept in an atmosphere
completely saturated with moisture. The results
secured by this treatment are presented in the table
on the preceding page.

The results of this experiment are quite striking.
In the cheese kept in air incompletely saturated with
moisture, there wa-s a steady loss, so that the cheese
which contained 36 per cent of moisture at the start
had its moisture content decreased to less than 25
per cent. On the other hand, the cheese kept in a
sa-turated atmosphere not only lost no moisture, but
actually gained water by absorption, so that its per-
centage of water was increased from about 36 per
cent at the beginning to nearly 38 per cent at the
close of the experiment. The two cheeses, which
contained the same percentage of moisture at the
beginning, were found to differ, at the end of 15
months, 13 per cent in moisture, solely as the result
of being kept in air containing different degrees of
moisture.

The same fact is well illustrated in experiments
made at the Wisconsin experiment station. A com-
parison was made of the relative humidity of the air
in a curing-room with that inside a closed cheese-
box, in which a cheese was kept.

Temperature

Relative

humidity in

room

Relative

humidity inside

cheese-box

Room 1

Room 2

Room 3

350.400 F,

50°-55°F.
60°-69° F.

Per cent
85-92
55-75
50-70

Per cent
100
94
84-90

RIPENING OF CHEESE 3I9

These results indicate that the storage of cheese in
boxes in curing--rooms is one means of avoiding the
results of too rapid loss of niois'ture. Of course, dif-
ficulty arises in the way of molds in the case of cheese
so stored, unless they are properly fumigated (p.
134) or covered with paraffin, a point which will be
considered next.

Protection of surface of cheese and loss of
weight. — The covering of the outer surface of
cheese with a layer of paraffin has been found to
diminish greatly the loss of weight. The first sugges-
tion of the practical use of paraffin in connection
with covering cheese came, so far as we know, from
the Standard Oil Company about 10 or 12 years
ago, when it advertised a preparation of yellow-
colored paraffin for use in protecting cheese from
mold. Some experiments were made at the Wis-
consin experiment station in 1899 to prevent mold
by the use of paraffin, but the results were not re-
garded as sufficiently satisfactory in every way to
justify its recommendation for general use. In ex-
perimental work at the New York experiment
station, cheese was covered ' with paraffin in order
to control moisture, without any reference to the
thought of practical application. The matter was
later taken up in a practical way here and in Can-
ada. The results of co-operative work between
the United States Department of Agriculture and the
experiment stations of Wisconsin and New York,
carried on in 1902-3, may be regarded as the first
demonstration in the United States that attracted
serious attention. Since then the practice has grown

320 SCIENCE AND PRACTICE OF CHEESE-MAKING

rapidly, but the primary object is quite as much pre-
vention of loss of weight as protection from mold.
The results of the work done at that time in New
York will suffice as a basis of discussion. Cheeses
weighing 70 pounds were used, some being covered
with paraffin, while others were left in the usual con-
dition. The results are given as follows:

Age

Pounds lost for 100 pounds of cheese

Cheese

Kept at
40°F.

Kept at
• 50°F.

Kept at
60°F. '

Normal

Weeks
17
17
25
25
32
32

2.5
0.3
3.1
0.6
4.5
0.9

2.4
0.5
4.0
0.9

4.2

Parafifined

1.4

Normal

Paraffined

Normal

Paraffined

By covering cheese with paraffin, a saving in loss
of moisture can be effected, amounting to 5 or 6
pounds per 100 pounds of cheese at 60° F. ; while at
50° F., and below, the total loss of moisture can be
reduced to less than i pound per 100 pounds of cheese.
In every case, cheeses covered with paraffin were
entirely clean, while the others were more or less
heavily coated with molds. The saving effected by
paraffining small-sized cheeses is even greater than
with those of larger size.

Size and shape of cheese in relation to loss of
weight. — The amount of external surface is greater
in relation to weight in the case of a small cheese than
of a larger cheese, and we should, therefore, expect
a larger loss of moisture.

RIPENING OF CHEESE

321

The following table illustrates the losses of weight
in the case of cheeses 7 inches in diameter ; this is
the type commonly known as "Young America."
They were made from one vat of milk and kept
at 65° F.

WEIGHT LOST BY CHEESES OF VARYING HEIGHT AND

UNIFORM DIAMETER

Water lost by 100 pounds

of green cheese in

Height

Weight
of

cheese

green

cheese

wk.

wks.

Inches

Pounds

Lbs.

4.6

3.4

5.3

6.4

7.0

10.7

12.9

13.9

15.9

17.0

6.1

3.3

5.1

6.1

6.7

9.7

11.5

13.0

14.0

15.6

7.9

2.8

4.2

5.5

6.3

8.3

9.8

11.2

12.6

13.4

9.3

2.5

3.9

5.2

7.8

9.4

10.6

11.6

12.8

11.0

2.3

3.4

4.7

5.6

7.4

8.9

10.5

11.2

12.4

The loss of weight decreases with increase in height.
Taking the total loss of weight for different periods
of time, it is seen that an increase of one inch in height
reduced the loss of weight per lOO pounds of cheese 5
ounces at the end of 4 weeks, 13 ounces at 8 weeks,
16 ounces at 12 weeks and 18 ounces at 20 weeks.

In the table on the next page we show the loss of
weight in the case of cheeses having different diameters
and kept at temperatures ranging from 55° to 80° F.
It is seen that, in general, the loss of weight increases
at all temperatures as the diameter increases, the dif-
ference being greater at higher temperatures.

Variation of loss of moisture with different kinds
of cheese. — In making small cheeses like "Young
Americas," and smaller sizes (p. 44) the propor-
tion of loss is much greater, and hence the demand

^22 SCIENCE AND PRACTICE OF CHEESE-MAKING

WEIGHT LOST BY CHEESES OF VARYING DIAMETER AND

UNIFORM HEIGHT

Tem-

Water lost by 100 pounds of cheese

Weight

pera-

Diam-

ture

eter of

green

cheese

curing-
rooms

wk.

wks.

Inches

Lbs.

Deg.P.

Lbs.

2.4

3.7

5.2

8.3

11.6

15.5

3.6

5.2

7.3

10.9

12.7

14.5

16.3

iV.i

2.2

3.3

4.7

7.2

9.7

11.4

3.1

4.8

6.6

9.2

11.1

12.7

14. i

is'.i

2.0

3.1

4.3

6.0

7.8

9.0

10.1

11.1

3.0

4.2

6.1

7.7

9.2

10.6

11.6

12.4

2.9

4.5

6.2

8.9

10.9

12.2

13.9

14.6

1.9

3.0

4.1

5.8

7.0

8.2

9.2

10.1

2.0

3.4

5.1

6.2

7.7

8.7

9.3

10.2

2.6

3.7

5.3

6.9

8.1

9.5

10.4

11.3

2.5

3.9

5.6

7.9

9.5

10.9

12.1

13.1

1.7

2.8

3.9

5.5

6.5

7.5

8.5

9.3

1.7

2.7

4.3

6.1

7.3

8.4

9.5

1.9

3.6

4.5

6.3

7.5

8.7

9.6

10.5

2.4

3.7

5.5

7.7

9.3

10.6

11.9

12.8

1.6

2.6

3.7

5.2

6.1

6.8

7.5

8.1

1.5

2.7

4.2

5.7

7.2

7.9

8.9

9.4

2.1

3.6

4.6

6.4

7.4

8.8

9.4

10.1

2.2

3.6

5.1

7.2

8.8

9.8

11.0

12.0

is still more imperative that these shall be cured
under conditions where the loss of moisture shall
be g-reatly reduced. This applies also to such
sizes as "Flats" and ''Twins." It is not surprising
that the manufacture of small cheeses of the ched-
dar type has been discouraged. Even at the
higher prices they bring, the extra loss of moisture
and additional cost of manufacture are not satisfac-
torily covered. In the manufacture of small, fancy
kinds of soft cheese, these statements do not apply,
because an essential part of the equipment consists of

RIPENING OF CHEESE

323

curing-cellars of fairly low temperature and high
moisture content.

Percentage of moisture in cheese and loss of
weight. — Below are given results obtained with
cheese made so as to contain water varying from 35
to 55 per cent when taken from press.

LOSS OF MOISTURE IN CHEESES CONTAINING DIFFERENT

PERCENTAGES OF WATER

Water in 100

Water lost by 100 pounds of green cheese

pounds of green
cheese

In 1 week

In 2 weeks

In 3 weeks

In 4 weeks

Pounds
55
50
45
35

Pounds
9.0
5.5
4.5
3.3

Pounds

11.2

9.2

6.3

4.2

Pounds

12.3

11.0

8.0

4.9

Pounds

16.8

12.9

9.5

5.7

These results show that the more moist a cheese
is when made, the greater is the proportion of water
lost by evaporation ; and, hence, the moisture in the
different cheeses tends to become more nearly alike
than at the start. Thus, cheese containing 55 per
cent of moisture lost about three times as much weight
as did the cheese containing 35 per cent of water and
nearly twice as much as the one with 45 per cent.
Even when cheeses do not differ so widely in water
content as those above, the same general rule holds
good, other conditions, of course, being the same.

Pounds of water in 100 pounds of green cheese .
Pounds of water lost by 100 pounds of green
cheese in 6 weeks

324 SCIENCE AND PRACTICE OF CHEESE-MAKING

Texture of cheese and loss of moisture. — Cheese
filled with holes will occupy more volume than the
same weight of cheese free from holes. Hence, cheese
with such faulty texture has a larger surface exposed
for evaporation relative to its weight and will lose

RIPENED AT 40°F

-t

t ' '

-. _^;^*ts^7- -Li^^^fism^jc^'r^ii:.

RIPENED AT 60^F

FIG. 45 — SECTIONS OF TWO CHEESES RIPENED AT DIFFERENT
TEMPERATURES. CLOSE-TEXTURED, CHEDDAR TYPE

more moisture. Then, in addition, the presence of
numerous holes in cheese greatly facilitates the escape
of moisture from the interior of the cheese to the sur-
face. This is a partial explanation of the fact that
cheese high in moisture loses water more rapidly

RIPENING OF CHEESE

325

than cheese containing less moisture. It is well
known that cheese containing high percentages of
water usually develops holes abundantly, especially
when cured at or above ordinary temperatures.

These statements are effectively illustrated in the
experiments carried on at the Wisconsin experiment
station; results are given for two distinct types of
cheese, which were used in studying the effects of
temperature during ripening: (i) Close-textured,

RIPENED AT 40°F

* %

RIPENED AT 60°F

FIG. 46 — SECTIONS OF TWO CHEESES RIPENED AT DIFFERENT
TEMPERATURES. SWEET-CURD TYPE

2,26 SCIENCE AND PRACTICE OF CHEESE-MAKING

firm-bodied, long-keeping type, suitable for export
trade, typical Wisconsin cheddars. (2) Sweet-curd
type, as represented by Iowa and Illinois methods of
manufacture. In connection with the table below,
study Figs. 45 and 46.

The following table gives the results in loss of
moisture in the cases of these two types of cheese :

LOSS OF MOISTURE

Type 1

Type 2

Type 1

Type 2

Age

(cheddar)

(sweet-curd)

(cheddar)

(sweet-curd)

when

ex-

amined

27 cheeses

9 cheeses

5 cheeses

kept at 40°F.

kept at 60°F.

Days

Per cent

0.38

0.69

0.96

1.05

0.44

0.82

1.74

1.77

0.58

0.96

2.05

2.29

0..83

1.15

2.95

3.67

1.00

1.42

3.57

■4.47

CHAPTER XXIV

Chemical Changes in Cheese-Ripening

In studying the chemical changes which take place
during the process of cheese-ripening, it will be an
advantage to consider the subject under the following
main lines of inquiry :

1. What chemical compounds are found in unripe
cheese ?

2. What chemical changes do the compounds of
unripe cheese undergo as cheese ripens?

3. W^hat conditions influence the character and
extent of these chemical changes?

4. What causes the chemical changes of cheese-
ripening?

The first three points will be considered in this
chapter, the fourth being reserved for a separate
chapter.

CHEMICAL COMPOUNDS IN UNRIPE
CHEDDAR CHEESE

Star*ting with unripe cheese as It comes from the
press, we find the same chemical compounds and
groups of compounds mentioned in connection with
the composition of milk, viz: (i) Water, (2) pro-
teins, (3) fat, (4) sugar, (5) neutral and acid
salts, (6) salt and (7) gases.

• Water. — The functions, amounts and ripening
losses of water in relation to cheese have already

327

^28 SCIENCE AND PRACTICE OF CHEESE-AIAKING

been considered. We shall later consider its rela-
tion to the chemical changes in cheese-ripening.

Proteins. — In cheddar cheese fresh from press,
there appear to be different protein compounds, the
precise nature of which has not yet been deter-
mined. There have been shown to be the follow-
ing forms: (i) Proteiji soluble in warm (122°-
131° F.), 5 per cent solution of sodium ^jilnrid,
which, for convenience, we shall speak of as brine-
soluble protein, (2) protein insoluble in brine solu-_
tion, and (3) proteins soluble in water. The first
constitutes the largest amount, often being 75 to
90 per cent of the total amount of proteins in ched-
dar cheese ; the water-soluble protein is quite fairly
constant, varying usually between 4 and 5 per cent
of the total proteins, and a part of this is readily
accounted for by the milk-albumin in the whey re-
tained in the cheese.

Fat. — The fat present in unripe cheese Is, in
composition and physical condition, essentially
milk-fat.

Milk-sugar. — The sugar in newly made cheese is
simply milk-sugar in solution in the whey that is
retained by the cheese.

Neutral salts and acid salts. — The most promi-
nent neutral salt in unripe cheese is calcium lactate,
formed as a result of the lactic acid (produced by
the fermentation of milk-sugar) upon the insoluble
calcium phosphate originally present in the milk, most
of which is carried into the cheese-curd and held
there. The soluble acid salts present in largest
amounts are calcium acid phosphate and, probably,
citrate.

CHEMICAL CHANGES IN RIPENING 329

Salt. — The unripe cheese contains common salt
which has been added to the curd in the operation
of cheese-making. This is held in solution, really
constituting a weak brine containing about 3 per cent
of salt.

Gases. — In normal, unripe cheese, gaseous prod-
ucts, except carbon dioxid, are present in only
minute amounts, if at all. In cheese made from
milk containing abnormal micro-organisms, there
may be present such gases as hydrogen, carbon di-
oxid, etc.

CHEMICAL CHANGES IN COMPOUNDS OF

UNRIPE CHEESE

We will now take up each division of the com-
pounds which we have considered briefly in the pre-
ceding section and notice some of the changes which
they undergo..

Water. — So far as we know, the water in cheese
undergoes no chemical change. It . gradually
evaporates from the cheese in the form of water-
vapor, the rate of evaporation varying with condi-
tions studied in the preceding chapter.

Proteins. — Of all the compounds contained in
unripe cheese, the proteins are the ones that are
most extensively affected by the chemical changes
of ripening, because these compounds are not only
the seat of those changes but the material itself
which undergoes chemical changes more profound
and complex than any other constituent of the
cheese. There have been and still are many diffi-
culties in carrying on a study of the chemical

330 SCIENCE AND PRACTICE OF CHEESE-MAKING

changes in cheese proteins during ripening, owing
largely (i) to a lack of detailed knowledge of the
compounds formed and (2) to need of more perfect
methods for estimating the amounts of these com-
pounds, many of which are formed only in very small
quantities.

Beginning with the milk-casein in the cheese-vat
at the time the rennet is added, we have, from that
time on, a succession of changes in the curd and
cheese, resulting sooner or later in the formation of
a series of compounds, which, so far as our present
knowledge goes, appears in something like the fol-
lowing consecutive order:

(1) Calcium paracasein (formed from the cal-
cium casein of milk by action of rennet). In-
soluble in water and in warm, 5 per -cent salt-brine.

(2) Protein soluble in warm, 5 per cent salt-brine.
(Figs. 30 and 31, p. 148.)

(3) Protein insoluble in salt-brine, water, etc.

(4) Proteins soluble in water:

(a) A protein which is precipitable by dilute
hydrochloric acid, called paranuclein.

(b) A protein substance coagulated in neutral
solution at the boiling point of water. This sub-
stan<:e appears to occur only rarely, except in the case
of cheese ripened near freezing point.

(c) Proteoses or caseoses (albumoses), whi^h
are proteins or p'rotein derivatives soluble in water,
not coagulated by heat, and usually precipitated by
saturating their solutions with zinc sulphate or am-
monium sulphate.

(d) Peptones, protein derivatives simpler than
the proteoses, soluble in water, not coagulated by

CHEMICAL CHANGES IN RIPENING 33I

heat, and not precipitated by saturation with zinc
sulphate or ammonium sulphate; precipitated by
phosphotungstic .acid, tannic acid and some other
reagents.

(e) Amino acids, the simplest protein deriva-
i'ves (except ammonia).

(f) Ammonia.

It would be beyond the scope of this book to go
further into the details of the chemistry of these
compounds, since they are very complex and require
a special knowledge of organic chemistry to under-
stand.

The amounts of these protein-derived products vary
with many conditions, some of which will be con-
sidered later (p. 337).

Fat. — There have been numerous investigations
made by different workers to ascertain whether the
milk-fat in cheese decomposes during the ripening
process. The general results of these investiga-
tions show that cheese-fat is unchanged milk-fat and
that these glycerin-acid compounds (glycerids) (p.
140) do not share extensively in the ripening proc-
ess, especially in the case of hard cheese, such as
cheddar. In one case, it was found that from i.o
to 7 per cent of the cheese-fat had undergone some
decomposition, the higher amounts occurring in
soft cheese. One of the early investigators (Blon-
deau) made several analyses of Roquefort cheese
at various ages and reported that the proteins of
the unripe cheese changed rapidly into fat. This
statement, though frequently disproved later, has
not even yet entirely disappeared from physiologi-
cal literature. The conclusions were based upon

332 SCIENCE AND PRACTICE OF CHEESE-MAKING

evident errors of analysis, which are readily appar-
ent on careful examination. More recent work,
however, claims that some organisms can change
casein into fatty acids, while this is especially
denied by another investigator. So far as we now
know, the matter appears to be one mainly of
academic interest, since the change must be insig-
nificant in amount, if it occurs at all. In all of
our extended work with cheese, we have found no
evidence of an increase of fat at the expense of
proteins. And no one has yet reported an accumu-
lation of fat in a separator skim-milk cheese during
the ripening process, where the conditions surely
furnish enough protein material for such a trans-
formation.

There is, however, one interesting condition
under which some fat appears to be changed, and
that is in case of cheese cured at low temperatures,
when we should ordinarily least expect such
change. It has been observed that, in cheese cured
near the freezing point of water, small white specks
may appear. These have been noticed at both the
Wisconsin and New York experiment stations as
well as in Europe. They have been supposed by
some to be salts of the cheese crystallized out in
little white aggregations, due to the dryness of the
cheese and the low temperature. One investiga-
tor has reported the spots as due to the result of
bacterial action on the fat in cheese, some of which
was decomposed, the decomposed portions forming
the minute white spots. Recently some cheese
filled with these white specks has been examined
at the New York experiment station; The white

CHEMICAL CHANGES IK" RIPENING 333

spots are about one-eighth the size of an ordinary
pin-head. They are more or less completely dis-
tributed through the mass of the cheese, appearing,
perhaps, more numerous or, at least, more promi-
nent in the lines where the pieces of curd are
cemented together. Wherever there is a mechani-
cal-hole, its walls are well covered and here the
specks appear specially prominent because they
simply lie on the walls and are not imbedded in
the body of the cheese. They can be easily de-
tached. When examined under a magnifying glass,
the small specks appear glistening white and also.
In some cases, the edges of the curd pieces, where
they are cemented together, have the same appear-
ance, very closely resembling paraffin. The specks
crush easily, like fat. An examination showed them
to contain calcium, but no phosphoric acid or other
inorganic salt in appreciable amounts. Besides
calcium, there appears to be some fatty acid, so
that the substance appears to be a calcium soap.
Some of the fat in the cheese is probably decom-
posed by bacteria acting only at low temperatures
and a reaction takes place between the fatty acid
set free and the calcium salts of the cheese. The
flavor and other qualities of the cheese do not ap-
pear to be affected in any appreciable way.

Milk-sugar in cheese, under the action of acid
organisms, completely decomposes, forming lactic
acid chiefly, with small amounts of some other
products. The sugar in fresh cheese may amount to
I or 2 per cent, but it seems to disappear from the
cheese, for the most part, in 48 hours and completely
within two weeks.

334 SCIENCE AND PRACTICE OF CHEESE-MAKING

Neutral salts and acid salts. — As already stated,
there rarely appears to be any free acid in normal
cheese. The calcium compounds (mainly phos-
phates and citrates) are sufficient in amount to
make use of the lactic acid which is formed, as
previously explained (p. 149). The same process
continues in the unripe cheese which previously
begins in the milk and curd in the cheese-vat. It
is probable that in ripened cheese the ammonia com-
bines with the acid salts to neutralize their acidity
more or less completely, because, in overripe cheese,
we usually find the reaction alkaline instead of
acid.

Salt. — So far as known, salt undergoes no chemical
change in cheese-ripening. As the water decreases,
the brine or whey of the cheese simply becomes
stronger, as a matter of course.

Gases. — In ripened cheese, different gases in dif-
ferent relative proportions have been found, but
little work has been done in connection with ched-
dar cheese. The amounts and kinds of gases un-
doubtedly vary according to various conditions,
depending primarily ( i ) upon the kinds of micro-
organisms introduced into the cheese through the
milk, and (2) upon the temperature at which
the cheese is ripened. The gases usually found in
largest amounts are carbon dioxld and hydrogen.
We have found also hydrogen sulphid. The dry
matter in cheese is slightly reduced, owing to the
formation and escape of gases. In one experiment
at the New York experiment station having for its
object a determination of the rate and amount of
carbon dioxld formed during ripening at 60° F. by

CHEMICAL CHANGES IN RIPENING 335

cheddar cheese, it was found that, under normal con-
ditions, the cheese began giving off carbon dioxid
gas at the start and continued to do so in increasing
amounts. At the end of two months, the rate of
formation was still near its highest and did not
begin to drop markedly until after about 20 weeks.
Measurable amounts of gas were still coming from
the cheese at the end of 32 weeks, when the experi-
ment was discontinued. The total amount of carbon
dioxid gas given off during the entire experiment
was equal to 0.5 per cent of the fresh cheese, while,
at the end of two months, it amounted to only o.i
per cent of the original weight of the cheese.

CONDITIONS OF CHEESE-RIPENING AND
CHEMICAL CHANGES

We have now considered the kinds of chemical
compounds present in unripe cheese and some of
the chemical changes which these compounds
undergo. It is known that many of these changes
take place gradually, some very slowly, but there
is a more or less definite progression of chemical
changes. The same cheese examined at intervals
is found to show quite marked variations in the
character of its proteins and protein-derived com-,
pounds. Cheeses made from the same milk under
the same conditions of manufacture and subjected
to different conditions during the ripening process
show a difference in chemical composition. Also,
cheeses manufactured under different conditions
and ripened under uniform conditions may vary
in the character of their nitrogen compounds. It

^^6 SCIENCE AND PRACTICE OF CHEESE-MAKING

is, therefore, important to know something of the
relation of various specific conditions to the forma-
tion of those products which are used as a measure
of the rate and extent of cheese-ripening.

Method of measuring rate of cheese-ripening. —
The development of flavor and the changes in body
characteristic of ripening cheese may be used as
indications of the rate and extent of the ripening
prooess, but such a method is too crude for accu-
rate work. Up to the present time, the most sat-
isfactory method has been to determine the
amount of different products derived from the pro-
teins of the unripe cheese. From a chemical point
of view, in which we consider solely the chemical
changes occurring, without reference to their cause,
cheese-ripening consists mainly of a change of in-
soluble proteins into water-soluble forms that con-
sist of other and simpler protein-derived com-
pounds, a list of which is given above (p. 330).
Hence, in a ripening cheese, we have progressively
increasing amounts of proteins or protein-derived
substances, and decreasing amounts of insoluble
proteins. Therefore, as a measure of the rate and
extent of ripening in cheese, we ascertain the
amounts of water-soluble proteins and protein-de-
rived substances and, from these amounts, reach
conclusions as to the degree of ripening that has
taken place. In many cases, the determination oi
the amounts of water-soluble and water-insoluble
substances alone is sufficient; while in others it is
necessary to know something in detail of the
amounts of each of the protein-derived constituents.
Stating the matter in a more comprehensive way,

CHEMICAL CHANGES IN RIPENING

337

the amount of water-soluble proteins and protein-
derived substances is used as a measure of the extent
of cheese-ripening, considered from a chemical stand-
point.

The special conditions to be studied in relation
to their influence upon the character and extent
of chemical changes in cheese-ripening are the fol-
lowing: (i) Time, (2) temperature, (3) moisture,
(4) size, (5) salt, and (6) rennet-enzym. From the
large number of data accumulated, we can give only
enough, in somewhat condensed form, to serve as
illustrations of the general facts discussed.

Time and cheese-ripening. — Under all normal
conditions that influence cheese-ripening, we find
that, as cheese advances in age, there is a progress-
ive change resulting in an increase of water-sol-
uble proteins and protein-derived substances. The
effect of time as a factor in cheese-ripening is modi-
fied by a variety of conditions, which will be con-
sidered later. For purpose of illustration, we give
below averages of the results obtained under the

SHOWING

EFFECT

OF TIME ON

CHEESE-RIPENING

Nitrogen, expressed as percentage of nitrogen in cheese, in form of 5

Water-

Age
of

Brine-
soluble

soluble
proteins

Para-

Case-

Pep-

Amino

Ammo-

cheese

protein

and de-
rivatives

nuclein

oses

tones

acids

nia

Months

Per cent

20.18

21.44

2.06

3.15

3.84

9.88

1.56

27.26

30.98

4.45

4.56

4.65

14.36

2.45

27.55

36.15

3.57

4.92

4.22

19.96

3.52

24.14

43.45

4.02

4.59

3.56

26.53

4.74

19.04

44.75

3.52

4.16

3.95

28.38

5.41

12.65

47.25

3.40

3.88

2.57

30.46

6.62

338 SCIENCE AND PRACTICE OF CHEESE-MAKING

various conditions employed. Each analysis rep-
resents the average of the results obtained with 24
different cheeses.

It is noticeable that all of the soluble forms of
nitrogen compounds increase in amount; while
some increase continuously, like amino acids and
ammonia, others increase for some months and
then decrease, as paranuclein, caseoses, and pep-
tones. Taking the total water-soluble forms in the
cheese at the end of 18 months, we see that, of the
total amount (47.25 per cent), 45.4 per cent was
formed in the first six weeks, 65.5 ' per cent in the
first 3 months, 76.5 per cent in the first 6 months,
and 92 per cent in the first 9 months, which is one-half
the entire period covered by our study. In gen-
eral, it is seen that, under uniform conditions, (i)
the formation of water-soluble proteins and protein
derivatives increases as cheese ages; (2) the rate of
formation of such compounds is more rapid in the
early stages of ripening, steadily diminishing with
^S^'y (3) about two-thirds of these compounds are
formed in the first 3 months and over 90 per cent in
the first 9 months.

Temperature and cheese-ripening. — In general,
we find in every individual cheese that temperature
exerts a marked influence upon the changes taking
place in the proteins. The effect of temperature
is, of course, modified by other conditions. As il-
lustrative of the effect of temperature, we give in
the table following averages in which each analysis
embodies the analytical results furnished by four
different cheeses ripened at the same temperatures.

CHEMICAL CHANGES IN RIPENING

339

We consider also the factor of time along with that
of temperature.

SHOWING EFFECT OF TEMPERATURE ON CHEESE-
RIPENING

Tem-
pera-

Form of
proteins

Nitrogen expressed as percentage of nitrogen ]

m cheese

ture of

curing-
room

and
derivatives

1*
mos.

mos.

6
mos.

9
mos.

mos.

18
mos.

Deg.F.

Per cent

Total water-

soluble . . ,

12.80

18.64

23.06

32.66

34.02

36.75

20.56

31.46

36.09

43.91

45.09

49.40

23.14

33.69

39.97

46.89

48.62

50.16

29.24

40.13

45.50

50.34

51.25

52.67

Brine-

soluble

20.58

43.14

36.55

43.00

34.48

21.37

(«

33.01

33.66

35.10

25.61

19.26

19.45

«C

13.89

18.81

19.94

16.15

12.32

9.45

13.24

13.45

18.62

11.83

10.10

7.86

Paranuclein

1.27

4.05

3.44

4.47

4.15

4.12

«(

2.39

5.34

4.25

4.27

3.64

3.68

2.54

2.71

3.90

4.23

3.59

4.73

2.03

3.71

2.68

3.13

2.45

2.60

Caseoses. .. .

1.05

2.97

5.24

4.29

4.17

5.06

4»

4.08

4.50

5.03

4.76

4.73

4.27

3.44

6.14

6.03

5.07

3.68

3.00

4.07

4.63

3.37

4.24

4.12

3.20

Peptones . .

1.30

2.23

4.53

4.36

4.53

4.17

• •

3.90

4.95

3.99

3.10

3.72

2.84

• •

3.33

5.99

4.70

3.44

4.03

1.80

• •

6.81

5.45

3.67

3.33

3.51

1.50

Amino acids

4.82

6.36

8.70

17.55

18.73

19.44

<«

8.69

14.33

19.55

27.05

29.00

31.66

<«

12.16

14.55

21.39

28.84

31.14

33.54

<«

13.86

22.20

30.80 .

32.68

34.65

37.19

Ammonia . .

0.61

1.21

1.91

2.14

3.98

• •

1.50

2.42

3.30

4.69

5.57

6.95

<•

• ■

1.67

2.54

3.89

5.43

6.12

7.35

••

• •

2.47

4.22

5.71

6.91

7.49

8.19

340 SCIENCE AND PRACTICE OF CHEESE-MAKING

Summarizing our results, we find that, other con-
ditions being uniform, (i) the water-soluble proteins
and derivatives in cheese increase, on an aver-
age, very closely in proportion to increase of tem-
perature; (2) from the average of our results, there
is an increase of 0.5 per cent of these water-soluble
compounds for an increase of one degree of tem-
perature between the limits of ^2° and 70° F. ; (3)
the amino acids and ammonia are formed in the cheese
more abundantly at higher temperatures and ac-
cumulate in the cheese, while the other water-soluble
compounds do not appear to be regularly influenced
by temperature in the early stages of ripening, but
after some months they decrease in quantity with
increase of temperature.

Moisture and cheese-ripening. — In order to study
the effect of moisture in cheese upon the chemical
changes taking place in the nitrogen compounds,
two sets of cheeses were made for comparison, 4
different cheeses in each set being made under
parallel conditions. One lot was covered with
melted paraffin, in order to retard the evaporation
of water from the cheese ; the others were left in
the usual condition. These cheeses were all kept
in the same curing-room at a temperature of 55°
F. In the tabulated results following, we give the
averages obtained with the 4 different cheeses in each
set of experiments, those that were covered with
paraffin being indicated as 2, the others as I.

The cheeses covered with paraffin had somewhat
less water when made, but the others lost water
more rapidly, so that at the end of 3 months their
water content was about the same. After this the

CHEMICAL CHANGES IN RIPENING

34 i

SHOWING EFFECT OF MOISTURE IN CHEESE ON CHEESE-
RIPENING

Form of
proteins
and de-
rivatives

Nitrogen expressed as percentage of nitrogen

in cheese

No.
of

cheese

mos.

1
2

Total water-
soluble . . .

Per cent

17.32
17.14

Per cent

27.09
27.40

Per cent

31.76
36.41

Per cent

39.09
46.59

Per cent

39.80

54.52

Percent

42.77
56.76

1
2

Brine-solu-
ble

24.89
21.17

41.59
30.42

35.43
49.29

28.81
20.16

21.70
9.81

13.72
5.30

1
2

Paranuclein
it

2.70
0.87

5.32
4.35

4.77
4.45

4.20
4.89

3.79
8.01

4.10
7.90

1
2

Caseoses . . .

2.99
3.58

5.80
3.64

4.24
5.38

4.41
5.06

4.19
4.32

4.26
4.70

1
2

Peptones... .
<<

2.12
4.49

4.09
4.80

3.75
6.19

3.57
4.00

3.97
4.43

1.95
3.20

Amino acids

7.50
7.22

9.79
12.59

16.00
17.12

21.65
26.03

22.89

29.44

26.73
29.00

Ammonia . .

1.34
0.98

2.15
1.99

3.04
4.26

4.17
6.52

4.53
8.27

S.72
12.16

1
2

Water

36.40
35.96

35.27
35.00

32.41
33.37

27.86
33.24

28.02
32.66

27.75
32.10

paraffined cheese contained considerably more water,
the difference increasing with age, until at the end
of 12 months it was over 4.5 pounds per 100 pounds
of cheese.

A general review of these results indicates the
formation of larger amounts of water-soluble nitrogen
compounds in cheese containing more moisture, other
conditions being uniform.

342 SCIENCE AND PRACTICE OF CHEESE-MAKING

Size of cheese and ripening. — On page 320 we
considered the influence of size of cheese upon the
rapidity of evaporation of water from the cheese.
Our results show that the percentage loss of mois-
ture is always greater in smaller-sized cheeses.
This is what might naturally be expected, since the
amount of external surface exposed for evaporation
is greater, relative to weight, in small than in large
cheeses. Hence, difference in size of cheese practi-

SHOWING EFFECT OF SIZE OF CHEESE ON CHEESE-
RIPENING

Form of

proteins

and de

rivatives

Nitrogen expressed as percentage of

nitrogen

in cheesi

W'ght

ot
cheese

mos.

3
mos.

6
mos.

mos.

12
mos.

18
mos.

Lbs.
10

Total water-
soluble. . .

Per cent

17.32
20.56

Per cent

27.09
31.46

Per cent

31.76
36.09

Per cent

39.09
43.91

Per cent

39.80
45.09

Per cent

42.77
49.40

10
30

Brine-solu-
ble

24.89
33.01

41.59
33.66

35.43
35.10

28.81
25.61

21.70
19.26

13.72
19.45

10
30

Paranuclein

£4

2.70
2.39

5.32
5.34

4.77
4.25

4.20
4.27

3.79
3.64

4.10
3.68

10
30

Caseoses . . .

2.99
4.08

5.80
4.50

4.24
5.03

4.41
4.76

4.19
4.73

4.26
4.27

10
30

Peptones . .

1 1

2.12
3.90

4.09
4.95

3.75
3.99

3.57
3.10

3.97
3.72

1.95
2.84

10
30

Amino acids

7.50
8.69

9.79
14.33

16.00
19.55

21.65
27.05

22.89
29.00

26.73
31.66

10
30

Ammonia . .

1.34

1.50

2.15
2.42

3.04
3.30

4.17
4.69

4.53
5.57

5.72
6.95

10
30

Water

36.40
36.31

35.27
35.11

32.41
33.46

27.86
32.29

28.02
31.54

27.75
28.56

CHEMICAL CHANGES IX RIPENING 343

cally means' difference in rapidity of loss of mois-
ture, the larger cheese retaining its moisture con-
tent longer. We should expect, then, to find es-
sentially the same differences of ripening in cheeses
of different size that we find in cheeses having a dif-
ferent moisture content. To make a study of this
point, we present on page 342 some data showing, at
different stages of ripening, the amounts of derived
protein compounds found in cheeses weighing respec-
tivety 30 and 10 pounds, approximately. The data
represent averages of 4 different lots of cheeses
ripened at 55° F.

An examination of the table shows, in brief, that
the larger cheeses contained more moisture after the
early stages of ripening and that there was a more
rapid increase in the formation of total water-soluble
derived proteins, especially of amino acids and am-
monia, than in the smaller cheeses.

Amount of salt and cheese-ripening. — It is a fact
that has long been observed by cheese-makers that
increase of salt in cheese delays the rapidity with
which the cheese becomes marketable, but, until
about five years ago, no detailed chemical results
were published in relation to the subject. In order
to study the influence of salt upon the ripening
process in cheese properly made and kept, there
were made, as nearly alike as possible, four different
lots of cheese under normal conditions. In each
lot there were 4 cheeses weighing 30 pounds each,
and salt was added to these in proportions varying
as follows: No salt, 1.5, 2.5, and 5 pounds of salt
for 1,000 pounds of milk. During the ripening, one
lot was kept at 32° F., one at 55° F., one at 60° F.
and one at 70° F, On page 345 we give the aver-

344 SCIENCE AND PRACTICE OF CHEESE-MAKING

ages of the 4 lots of cheese kept at the different tem-
peratures. Whether we consider each lot of cheeses
by itself or their averages, the results are strikingly
concordant in respect to the effect of salt upon the
formation of proteins and their derivatives in the
ripening process.

We are to regard the salt in cheese as being in
solution in the whey held by the cheese, practically
forming a dilute brine. In common practice,
cheese-makers add from 2 to 2^ pounds of salt to
the curd made from 1,000 pounds of milk. Cheese
thus salted contains about i per cent of salt. Such
cheese usually contains about 35 to '^^y per cent of
water. Consequently, under such conditions we
should have, approximately, a 3 per cent brine. It
is evident that, in proportion as a cheese loses mois-
ture by evaporation, the brine remaining becomes
more concentrated with the advancing age of the
cheese.

A study of the table leads to the following state-
ments :

(i) The amount of salt retained in cheese is not
proportional to the amount of salt added to the curd.
While salt was added to the different cheeses in the
ratio of i: 1.67: 3.33, the salt retained in the cheese
was in the ratio of 1:1.40:2.20. Of necessity,
a considerable proportion of the salt added to the
cheese-curd passes into the whey. Moreover, it
has been found by examining different portions of
the same cheese that the salt is not commonly
distributed with perfect uniformity through the cheese
mass.

SHOWING EFFECT OF SALT ON CHEESE-RIPENING

Am't

of salt
used

Form of
proteins

Nitrogen expressed as percentage of nitrogen

in cheese

for

1000

and de-

lbs.

rivatives.etc.

mos.

of milk

Lbs.

Total water

Per cent

' Percent

Per cent

soluble ....

23.42

34.26

40.52

49.10

51.38

53.96

( (

21.80

32.10

37.67

44.13

45.88

50.73

( t

21.67

29.92

34.73

42.93

43.52

44.65

18.84

27.70

31.70

37.64

38.19

39.62

Brine-solu-

ble

17.33

27.06

23.27

21.82

16.75

12.56

((

20.86

28.43

26.16

22.38

17.98

12.61

21.81

24.47

28.30

23.54

18.04

13.7'

20.73

29.02

32.49

28.81

23.41

11.7*

Paranuclein

1.85

4.44

3.80

4.66

3.83

3.44

2.13

4.47

3.52

4.01

3.72

3.89

2.27

4.55

3.51

3.80

3.30

3.34

1.98

4.35

3.42

3.63

3.23

2.96

Caseoses . . .

3.41

4.94

5.60

4.95

3.87

3.24

5.02

5.17

4.53

3.69

4.04

<•

3.21

4.14

4.98

4.16

3.97

3.84

• • •

2.75

4.14

4.58

4.08

4.05

3.77

Peptones . .

4.86

5.02

4.84

3.47

4.13

2.69

3.50

5.16

4.29

3.54

4.87

3.40

•<

4.20

4.02

3.97

3.98

2.07

• •

2.91

4.42

3.74

3.25

2.81

2.14

Amino acids

10.22

15.86

22.18

28.89

32.19

35.09

«<

10.46

14.77

20.13

27.31

29.33

32.36

t«

9.78

13.83

19.20

26.72

27.61

29.57

8.82

12.97

17.34

23.21

24.40

24.81

Ammonia . .

1.67

2.96

4.64

6.54

7.77

8.89

1.67

2.53

3.69

4.69

5.36

7.04

1.51

2.36

3.13

4.30

4.54

5.83

• •

1.41

2.03

2.64

3.43

3.61

4.70

Per cent
water in

cheese ....

39.27

38.22

35.60

35.22

34.C9

30.96

36.66

35.60

33.50

32.62

31.61

28. 8C

35.69

34.43

32.31

. 31.54

30.99

27.68

33.63

32.62

29.52

29.88

28.61

26.93

Per cent salt

in cheese. .

((

0.59

0.70

0.84

0.94

0.92

• • • •

0.82

1.20

1.15

1.26

1.27

• • • •

1.29

1.50

1.62

1.87

1.83

• • •

346

346 SCIENCE AND PRACTICE OF CHEESE-MAKING

(2) An increase of salt in cheese-curd results in
decreasing the amount of moisture held in cheese.
This fact is very strikingly shown by the figures in
the table. The cheese containing no salt retained
most moisture, and increasing additions of salt de-
creased the amount of moisture held in the cheese.
The same general relation held true throughout the
whole period of investigation.

(3) An increase of salt in cheese was accom-
panied by a decrease in the amount of water-soluble
protein-derived compounds and- this was true
through the whole 18 months of the investigation.
While this influence of salt is more noticeable in the
case of the amino acids and ammonia, it is -clearly
evident in the case of the paranuclein, caseoses, and
peptones.

(4) It is readily seen from the results embodied
in the table that the rapidity of formation of water-
soluble protein-derived compounds is decreased in
the presence of increased amounts of salt in cheese.
This is due, in part, to the effect of salt in decreas-
ing the amount of moisture held in cheese and, in
part, to the direct retarding action of salt upon some
of the agents that produce the changes of cheese-
ripening.

Amount of rennet-enzym and cheese-ripening. —
Before any careful studies were made of the effect
of rennet-enzym upon the chemical changes of
cheese-ripening, there was difference of opinion
among cheese-makers as to whether the amount
of rennet-extract used had any influence on the
ripening of the cheese. The various studies made
of the subject by different investigators agree in

CHEMICAL CHANGES IN RIPENING

347

that rennet-enzym does influence the
rapidity of the ripening process. In the results

showing

SHOWING EFFECT OF DIFFERENT AMOUNTS OF RENNET

UPON CHEESE-RIPENING

Amount

of
rennet-

Nitrogen expressed

as percentage

Condition

Water

of nitrogen in cheese in form of;

Age

extract

Water-

cheese

used for

cheese

soluble

Paranu-

1000
pounds

proteins
and de-

clein. cas-
eoses and

Amino
acids

Ammo«
nia

of milk

rivatives

peptones

Months

Ounces

Per ct.

Perct.

Normal.. . .

37.54

18.90

10.31

8,36

• a • •

Normal.. . .

38.06

23.40

13.37

9.47

■ a • •

Paraffined .

38.45

18.20

9.95

8.29

• ■ • •

Paraffined..

38.56

24.90

15.30

9.63

....

Normal.. . .

35.59

26.70

13.34

12.00

1.87

Normal.. . .

36.25

29.70

15.40

12.50

1.86

Paraffined..

37.97

27.90

13.39

12.60

1.96

Paraffined..

37.61

33.20

16.35

14.70

2.18

Normal.. . .

33.58

29.80

12.02

16.20

2.09

Nonnal.. . .

33.51

35.40

15.11

18.20

2.60

Paraffined..

37.59

31.80

12.84

17.30

2.23

Paraffined..

36.79

36.80

16.76

17.30

2.70

Normal.. . .

31.84

37.30

13.47

21.20

2.59

Normal.. . .

30.63

35.50

13.00

20.00

2.50

Paraffined..

36.81

38.90

14.93

20.30

3.73

Paraffined..

35.40

45.20

14.36

26.60

4.26

Normal,. . .

28.13

38. oa

12.05

22 10

4.10

Normal.. . .

29.98

42.40

14.38

24.00

3.60

Paraffined..

36.07

40.40

14.10

23.60

2 93

Paraffined..

34.51

48.10

15.34

27.50

4.60

Normal.. . .

26.73

39.10

12.05

22.90

4.53

Noi-mal.. . .

25.97

43.60

13.19

25.50

4.31

Paraffined..

34.35

41.20 ,

12.96

23.80

4.92

Parafined...

33.21

49.90

16.87

28.00

5.54

Normal.. . .

24.76

42.70

12.30

25.10

5.06

Nonnal.. . .

23.33

48.50

14.54

28.50

5.84

Paraffined..

30.93

46.40

11.34

28.70

6.52

Paraffined..

28.22

50.20

11.75

30.80

7.92

348 SCIENCE AND PRACTICE OF CHEESE-MAKING

given on page 347, the study was made with the use
of 3 to 6 ounces of Hansen's rennet-extract in 1,000
pounds of milk. The cheeses were made to con-
tain about the same amount of moisture. In each
case, one cheese was covered with paraffin in order
to delay the evaporation of moisture, while the other
was kept in the usual condition.

The data in the preceding table show quite gen-
erally a greater increase of water-soluble protein-
derived compounds in the cheese containing the
larger amount of rennet, other conditions being the
same. The cheeses covered with paraffin contain
more moisture than those not so covered and, as
we should expect, show a larger increase of soluble
compounds than do the other cheeses ; but here, also,
the cheese containing the larger amount of rennet
ripens more rapidly than the one containing less
rennet.

If we examine the different classes of the water-
soluble protein and protein-derived compounds, we
notice that the increase caused by the increased
use of rennet is more noticeable in the case of the
paranuclein, caseoses and peptones than in the case
of the amino acids and ammonia, especially during
the first 6 or 9 months.

GENERAL SUMMARY OF RESULTS RELAT-
ING TO CONDITIONS OF CHEESE-
RIPENING AND CHEMI-
CAL CHANGES

Reviewing briefly the results that have been pre-
sented in the preceding pages, we have found that

CHEMICAL CHANGES IN RIPENING 349

different conditions affect the chemical changes in
the protein compounds of cheese as follows :

(i) Time. — The formation of water-soluble pro-
tein-derived compounds increases as cheese ages,
other conditions being uniform. The rate of increase
is, however, not uniform, since it is much more rapid
in the early than in the succeeding stages of ripen-
ing.

(2) Temperature. — The amount of soluble pro-
tein-derived compounds increases, on an average, quite
closely in proportion to increase of temperature, when
other conditions are uniform.

(3) Moisture. — Other conditions being alike,
there is formed a larger amount of water-soluble
protein-derived compounds in cheese containing
more moisture than in cheese containing less mois-
ture.

(4) Size. — Cheeses of large size usually form
water-soluble compounds more rapidly than smaller
cheeses under the same conditions, because large
cheeses lose their moisture less rapidly and after
the early period of ripening have a higher water
content.

(5) Salt. — Cheese containing more salt forms
water-soluble compounds more slowly than cheese
containing less salt. This appears to be due, in
part, to the direct action of salt in retarding the
activity of one or more of the ripening agents and,
in part, to the tendency of the salt to reduce the
moisture content of the cheese.

(6) Rennet. — The use of increased amounts of
rennet-extract in cheese-making, other conditions
being uniform, results in producing increased

350 SCIENCE AND PRACTICE OF CHEESE-MAKING

quantities of water-soluble protein-derived compounds
in a given period of time, especially such compounds
as paranuclein, caseoses and peptones.

TRANSIENT AND CUMULATIVE PROD-
UCTS IN CHEESE-RIPENING

In studying the influence of various conditions
upon the chemical changes of the protein com-
pounds in the normal cheese-ripening process, we
have noticed that the compounds which are grouped
under the names, paracasein, caseoses and peptones
usually vary within comparatively narrow limits
and do not appear to accumulate in the cheese in
constantly increasing quantities. These compounds
do not appear to show much definite regularity
in the amounts formed under different con-
ditions. On the other hand, amino acids and am-
monia accumulate in increasing amounts from the
early age of the cheese during the whole process
of normal ripening. The difference in the appar-
ent behavior of these different classes of com-
pounds is most readily explained by regarding the
compounds first formed in cheese-ripening as inter-
mediate or transient products. Thus, we find para-
nuclein, caseoses and peptones present in the earliest
stage of cheese-ripening, and they show a tendency
to increase somewhat for a period of time and then
decrease. Whatever may be the precise chemical
relation and order of formation, the point we wish
to keep in mind is that the amounts of these com-
pounds do not increase regularly or accumulate
continuously in the cheese. The extent to which
any accumulation occurs in these transient stages

CHEMICAL CHANGES IX RIPENING

351

depends upon the conditions of ripening. For ex-
ample, at low temperatures, the transient protein
products formed appear to pass into other forms less
rapidly than at higher temperatures, and they tend to
accumulate to some extent. This can be shown by
comparing the results secured with cheeses ripened at
2,2° F. and at 70° F.

Age

cheese

Percentage of ni-
trogen in form of
paranuclein in
cheese at

Percentage of ni-
trogen in form of
caseoses in
cheese at

Percentage of ni-
trogen in form of
peptones in
cheese at

32°F.

70°F.

32°F.

/0°F.

32°F.

70°F.

Months

li
3

6
9

12
18

Per cent

1.27

2.03

1.05

4.0/

1.30

4.0s

3.71

2.97

4.63

2.23

3.44

2.68

5.24

3.37

4.53

4.47

3.13

4.29

4.24

4.36

4.15

2.45

4.17

4.12

4.53

4.12

2.60

5.06

3.20

4.17

Per cent
6.81
5.45
3.67

3.51
1.50

Now, quite different from the behavior of these
compounds is that of amino acids, which appear be-
yond question to be formed from the peptones, and
of ammonia, which is formed from the decomposition
of amino acids. Ammonia is an end-product and the
amino acids are end-products to a considerable extent
in cheese normally ripened. They therefore accum-
ulate in increasing quantities under all conditions
that favor their formation.

INFLUENCE OF PRODUCTS OF CHEMICAI,
CHANGE IN THE CHEESE-RIPENING

PROCESS

Attention has been called to the fact that chemi-
cal changes in the proteins of cheese take place

352 SCIENCE AND PRACTICE OP CHEESE-MAKING

much more rapidly in the early stages of ripening
than later. It is shown that, in the first 3 months
of the 18-month period of study, over 65 per cent
of the nitrogen was changed into the form of
water-soluble compounds. How can we explain
this observed fact that the rate of chemical change, as
measured by the formation of water-soluble ni-
trogen compounds, decreases as the age of cheese
increases? The most obvious explanation is asso-
ciated with the generally observed fact that in fer-
mentation changes the products of the process
weaken the action of the ferment, often inhibiting
it altogether (p. 286). In cheese, we have an ac-
cumulation of fermentation products in the form of
water-soluble protein and protein-derived compounds
and, apparently, they serve to diminish the action of
the agents that cause the changes.

In this connection, it is interesting to notice that
the end-products, the amino acids and ammonia,
appear to exert a stronger influence than do the other
soluble protein compounds in decreasing the action of
the ripening agents. This is indicated by the fol-
lowing data :

Monthly average

Percentage of

rate of increase of

Age
of

nitrogen in form of

soluble nitrogen

paranuclein, caseo-

amino acids and

compounds for 100

cheese

ses and peptones

ammonia

pounds of nitrogen
in cheese

Months

Pounds

9.05

11.44

15.0

13.66

16.81

6.3

12.71

23.48

2.1

12.17

31.27

2.4

11.63

33.79

0.4

....

37.00

0.4

CHEMICAL CHANGES IN" RIPENING 353

Thus, it is seen that the first-formed products of
cheese-ripening, paranuclein, caseoses and peptones,
remain fairly uniform, while the amino acids and am-
monia continuously increase.

WHY MOISTURE INFLUENCES THE
CHEESE-RIPENING PROCESS

We have seen that an increased moisture content
in cheese favors more active chemical changes in
the process of ripening. This may be due to one or
both of two effects. First, moisture in itself may
favor the activity of the ripening ferments. It is well
known that moisture is necessary for the action of
ferments and that increase of moisture above a certain
amount increases their action. Second, the presence
of increased amounts of moisture serves to dilute the
fermentation products and, to that extent, to counter-
act their unfavorable effect.

In ordinary cheese-ripening, there is a constant
loss of moisture and this serves to make more con-
centrated the fermentation products, which are
increasing at the same time the moisture is de-
creasing. Accordingly, after 3 to 6 months, differ-
ence in moisture appears to exert a more marked
influence upon the increased formation of soluble
nitrogen compounds than in the early stages of
ripening.

CHAPTER XXV

Causes of Chemical Changes in Cheese-

Ripening

A large amount of work has been done during the
past 30 years in connection with different varieties
of cheese, in an effort to ascertain what agents cause
the changes taking place in cheese during the ripen-
ing process. Many of the results have been peculiarly
confusing and progress has been slow. Much of this
work has been done with the hard types of cheese,
the Emmenthaler in Europe and the cheddar in Eng-
land and America. The scope of this book does not
permit an historical review of these investigations,
and the most we can hope to do, within the assigned
limits of treatment, is to give a brief summary of
what may be regarded as the present state of knowl-
edge in respect to the causes of cheese-ripening in
the case of cheddar cheese. It is well to preface our
discussion with the statement that the amount we
actually know at present is disappointingly small, and
how much of what we think we know now will be
modified by further investigation no one can con-
fidently say. In our treatment of the causes of cheese-
ripening, we confine our attention mainly to the
changes that take place in the protein compounds,
which come originally, as we know, from milk-casein ;
because, in this portion of the cheese substance, the
most profound and extensive changes occur, changes

364

CAUSES OF RIPENING CHANGES 355

which are most intimately comiected with the chang-
ing qualities that appear in the process. As pre-
viously stated, the cheese-ripening process, considered
from a chemical standpoint, consists mainly in the
change of the complex protein, paracasein, as it exists
in cheese-curd, into a number of less complex com-
pounds.

Many difficulties beset the experimental study of
cheese-ripening, some of which will be briefly noticed
later. One of the great difficulties in the past has
been a failure to recognize that there was more than
one agent at work in the process of cheese-ripening.
The investigator is always at a disadvantage when
his point of view is too narrow, since he inevitably
overlooks essential details, and interprets his results
within the narrow range of his vision. This truth has
been amply illustrated in the history of the investiga-
tion of the causes of 'cheese-ripening, since many in-
vestigations were based upon the conception that only
one agent was the cause; and the object of the inves-
tigator was, unconsciously, not so much to find out
what the real cause might be as to show that the one
particular agency he had in mind was the actual and
sole cause.

We shall not attempt to treat the subject in the
order of its historical development, but rather in the
order in which the different agencies become most
active in the ripening process. So far as our pi-esent
knowledge goes, the different agents taking part in
the change of the protein, paracasein, into simpler
proteins and protein-derived compounds are the fol-
lowing :

I. Some acid, usually lactic.

356 SCIENCE AND PRACTICE OF CHEESE-MAKING

2. Rennet-enzym.

3. Galactase.

4. Micro-organisms, commonly bacteria.

Just what part is played by each agent in the forma-
tion of water-soluble proteins and derived proteins,
or what interdependence there may be of the work
of one agent upon the products of the work of
another, we are at present able to say only in part,
and not very definitely at that. We will now present
an outline of what we may conceive as the distribu-
tion of work among these different agents in the light
of the experimental results that are now available.
We are conscious of the possibility, or rather prob-
ability, that some of these statements will need
revision in the near future.

ACTION OF ACIDS IN CHEESE-RIPENING

The necessity of the presence of some acid in milk
and in cheese-curd during the process of making
cheddar cheese seems to have been well established,
since cheese made without acid fails to ripen satis-
factorily. In the absence of acid, little or no brine-
soluble protein or water-soluble substance is formed,
even after long periods of time. The work of acid,
whatever may be the way in which its specific influ-
ence is exerted in cheese-ripening, is something like
this : Lactic acid is formed by the action of micro-
organisms upon milk-sugar during the process of
cheese-making; and its formation continues not only
during the time the curd is in the cheese-vat but
also in the curd as it is put in the press and later.
Under normal conditions, the acid continues to be
formed so long as any milk-sugar remains in the

CAUSES OF RIPENING CHANGES

357

cheese. Just how long that is, varies according to
conditions of manufacture and especially with the
temperature at which the cheese is kept during the
ripening.. Under ordinary conditions, all sugar in
cheese disappears within two weeks. Roughly
speaking, there is between i and 2 per cent of milk-
sugar in cheese when put in the press. How rapidly
this undergoes change can be seen from the following
illustrations, in which three different cheeses are
represented :

MILK-SUGAR IN CHEESE

No. 1

When put in press

3 hours after being in press
6 hours after being in press
12 hours after being in press
15 hours after being in press
2 days after being in press. . ,
4 days after being in press. .

1 week after being in press. .

2 weeks after being in press.

Per cent
1.70
1.05
0.68
0.68
0.58
0.58
0.50
0.10
0.07

No. 2

Per cent
0.77
0.68
0.44

0.10
0.04
0.03
0.00

No. 3

Per cent
1.52
0.64

o'.so

0'.36

0.32

0.22

trace

These figures illustrate well the great variation in
detail that may occur in the disappearance of milk-
sugar in cheese, which means, of course, the forma-
tion of lactic acid.

At no stage of the process of making cheddar
cheese, and in no cheese, do we find, under normal
conditions, uncombined lactic acid as such, or what
we call free lactic acid. What then becomes of the
lactic acid known to be formed? There exist in the
milk substances which are ready to combine with
lactic acid as fast as it is formed and to change the
acid from the active condition of a free acid to that

358 SCIENCE AND PRACTICE OF CHEESE-MAKING

of a neutral salt. These substances are chiefly lime
compounds or compounds containing calcium as a
base. Over one-half and, probably, about three-
fourths, of the calcium compounds in milk are in such
form as enable them to combine with lactic acid. A
considerable part of the calcium in milk is in com-
bination with phosphoric acid in the form of insoluble
compounds, probably dicalcium phosphate in large
part, which is held in suspension in the form of very
minute, solid particles. Some believe that the cal-
cium phosphate is in direct combination with casein
in milk. The action that probably takes place can be
represented as follows :

Lactic acid -f- insoluble calcium phosphate = cal-
cium lactate -f- soluble calcium phosphate (mono or
acid-calcium phosphate). Now, mono-calciimi phos-
phate is an. acid salt ; it neutralizes alkalis and tastes
sour. Therefore, when we talk about lactic acid in
cheese-making, we really mean the products formed
by the action of lactic acid — calcium lactate and cal-
cium acid phosphate.

The first effect of the formation of these soluble
lime salts is to promote the coagulating effect of
rennet; and the particular thing accomplished by
ripening milk for cheese-making is the formation in
small, but sufficient, quantities of cakium lactate and
soluble calcium phosphate. The succeeding changes
in curd, the formation of a superficial film on each
small piece of curd, the shrinking with the simul-
taneous expulsion of whey, the stringing on a hot
iron, the change in texture of curd to the softer,
velvety form, resembling the meat of a chicken's
breast, the plastic condition — these changes all

CAUSES OF RIPENING CHANGES

359

appear to be associated with the continued forma-
tion of lactic acid, resulting in larger amounts of
calcium lactate and acid phosphate. To what ex-
tent temperature and action of rennet-enzym share
in producing these changes cannot be definitely
stated now. It has been pretty satisfactorily estab-
lished that in cheddar cheese-making there is, con-
trary to what was believed at one time, no
combination of any kind between the lactic acid and
the protein of the cheese-curd, but that the acid
formed is practically all used by the lime salts of
the curd in the formation of the calcium compounds
mentioned.

During the cheese-making process, the cheese-curd
or paracasein undergoes some very marked changes,
as we have just noticed above. We have a simple
means of measuring the extent of these changes,
depending on the behavior of the curd when treated
with warm (123° to 132° F.), dilute brine (a 5 per
cent solution of common salt in water) (p. 330).
The changes taking place and thus measured can be
illustrated as follows, using the results of a special
experiment, taken from the records of the New York
experiment station :

Per cent of pro-
tein soluble in
brine solution

Per cent of pro-
tein soluble in
water

When curd was cut

3.13

4.50

30.15

46.46

96.06

When whev was removed

When curd was put in press

2 hours after curd was put in press
9J hours after curd was put in press

3.77
4.25
6.48

It is seen that the increase of the brine-soluble
protein is very rapid between the time when the whey

3t>0 SCIENCE AND PRACTICE OF CHEESE-MAKING

was removed and the curd was put in press. The
pecuHar behavior of the curd during the cheddaring;
process is probably due to the formation of the
brine-soluble substance; and the formation of this
substance appears to be associated, at least in consider-
able measure, with the formation of soluble lime salts
resulting from the action of lactic acid. From some
work done at the New York experiment station, it
seems that when this brine-soluble compound is not
formed, we do not get water-soluble substances,
and this means that we get no cheese-ripening. In
other words, the formation of the brine-soluble sub-
stance appears to be prerequisite to further ripening
changes.

Reviewing briefly the action of acid in cheese-mak-
ing and cheese-ripening, its chief work appears to be
combination with the insoluble lime salts of the
milk, producing calcium lactate and calcium acid
phosphate. These compounds, in conjunction with
the degree of heat used and, perhaps, also in asso-
ciation with the action of rennet-enzym, produce
marked changes in the curd in respect to body,
texture and solubility in brine solution. In the
cheese-making process, the insoluble portion of
the curd begins to change into a form that is soluble
in warm, 5 per cent brine, this change taking place
rapidly during the cheddaring operation and con-
tinuing until all the protein of the curd is in this
form; the change appears to be complete 9 or 10
hours after the curd is put in press. Then this
brine-soluble curd begins to change into an in-
soluble form, this reverse change going on very
rapidly for a few hours and then more gradually for
many months. From this insoluble form appear to

CAUSES OF RIPENING CHANGES 361

come the water-soluble proteins and protein deriva-
tives that are found in cheese. Much work yet re-
mains to be done before all the details of the action
of acid in cheese-making' are fully understood.

ACTION OF RENNET-ENZYM IN CHEESE-
RIPENING

For a long time, there was doubt as to whether
rennet-extract had anything to do with cheese-ripen-
ing. It may be now regarded as definitely settled
that rennet-extract contains a peptic ferment which
has a curd-dissolving power. This fact has nothing
necessarily to do with the question as to whether the
peptic enzym is the same as the coagulating enzym,
or whether two different enzyms, each with a dif-
ferent function, are present. The action of rennet
in cheese-ripening is quite similar to that of a pepsin
digestion. There is one important condition for the
peptic action of the rennet-enzym — the presence of
an amount of acid or acid salts, corresponding to
about 0.3 per cent of lactic acid. The acid produced
in cheese-curd and cheese furnishes the needed con-
ditions. Whether this is the chief function of acid
in connection with the formation of water-soluble
proteins and derived proteins in cheese-ripening, or
whether the salts formed by lactic acid exercise some
influence apart from rennet action, may not be re-
garded as satisfactorily determined at the present time.

In order to study the effect of rennet-enzym in dis-
solving the insoluble protein of cheese-curd, it is
necessary to destroy the enzyms and micro-organisms
present in milk. This is done by heating the milk
to a temperature of 185° to 208° F., after which the

2fi2 SCIENCE AND PRACTICE OF CHEESE-MAKING

milk is cooled and, in order to prevent bacterial action,
treated with chloroform before being made into
cheese. The heating of the milk to the stated tem-
perature diminis'hes the readiness and completeness
with which the rennet-extract coagulates milk-casein ;
but the power of prompt coagulation by rennet can
be restored by addition of calcium chlorid or carbon
dioxid gas or any ordinary acid or acid salt. In thus
eliminating other factors o'f cheese-ripening than ren-
net-enzym, we necessarily produce conditions that
do not exist in normal cheese-making, such as (i)
heated milk, (2) absence of milk-enzyms, (3) absence
of enzym-forming or acid-producing micro-organisms,
and (4) the addition of calcium chlorid or carbon
dioxid or lactic acid. Several experiments were car-
ried on at the New York experiment station under
the foregoing conditions and, in the table following,
we give some of the results of this work. Lactic acid,
when used, was added to form 0.2 per cent of the milk.

PEPTIC ACTION OF RENNET IN CHEESE WITH AND

WITHOUT ACID

Age of

cheese

when

analyzed

Cheese

made

with or

without

acid

Percentage of nitrogen in form of:

Water-soluble
proteins and

derived
compounds

Brine-
soluble
proteins

Paranuclein,
caseoses and
peptones

Amino
acids

Fresh

12 months

Without
With

6.07

4. 55

8.47

25.10

3.75
26.80

3.36
11.59

5.46

3.78

4.51

20.87

0.81
0.77
3.96
4.98

In studying this table, we can readily observe the

following indications

CAUSES OF RIPENING CHANGES 363

(i) When no acid, or acid salt, is present in the
cheese-making process, practically no changes take
place in the protein of the green cheese, even in the
course of a year; the different classes of compounds
remain about the same in amount at the end of a year
as in the fresh cheese. Rennet-enzym, in the ab-
sence of acid or acid salts, has practically no dissolv-
ing eft'ect on the protein of green cheese and, there-
fore, does little or no work in the formation of water-
soluble protein in the process of cheese-ripening.

(2) When lactic acid was added to milk at the
rate of 0.2 per cent, the results were in marked con-
trast with those given when no acid was used. Thus,
we have (a) a considerable amount of brine-soluble
protein in the fresh cheese, and (b) a large increase
of water-soluble nitrogen compounds at the end of
12 months. It is noticeable that the increase in these
water-soluble compounds is largely confined to the
paranuclein, caseoses and peptones; the amount of
amino acids remains small as compared with a normal
cheese of the same age.

That rennet-enzym acts like pepsin in dissolving the
protein of fresh cheese-curd has been shown by
experimental work. Heated milk (lOO cubic centi-
meters), treated with chloroform to prevent bacterial
action, was put into sterilized bottles ; 0.22 cubic cen-
timeter of Hansen's fresh rennet-extract was added
to some bottles, and to others 0.06 gram of aseptic
scale-pepsin for each 7 grams of protein in milk. In
the case of one-half of the bottles, 0.5 cubic centimeter
of pure lactic acid was added. The bottles were kept
at 60° F. The germ content was shown to be insig-
nificant. In one set of experiments milk was used

364 SCIENCE AND PRACTICE OF CHEESE-MAKING

and in another, cheese. The results obtained with
rennet-extract and commercial pepsin in the case of
milk are given below.

COMPARISON OF DIGESTING ACTION OF RENNET-EXTRACT
AND COMMERCIAL PEPSIN

Kind of

With or

without

lactic acid

Age of

milk

when

analyzed

Percentage of total nitrogen in form of:

enzym

material

used

Water-soluble
proteins and
derivatives

Caseoses

and
peptones

Amino
acids

Without

With

Without

With

Without

With

Without

With

Months
Fresh
1

1
1
1

3
3
3
3

6
6
6
6

9
9
9
9

9.98
11.96

8.91
27.52
33.51

16.44
11.42
39.17
44.47

15.95
10.34
44.00
48.76

18.00
10.08
50.77
56.96

*5"s6

2.22
20.39
25.93

8.06

2.42

29.01

34.22

12.74

6.60

38.46

44.74

12.90

6.51

42.66

48.05

Rennet . .
Pepsin . . .
Rennet.. .
Pepsin . . .

Rennet. . .
Pepsin . . .
Rennet.. .
Pepsin . . .

Rennet. . .
Pepsin . . .
Rennet. . .
Pepsin . . .

Rennet.. .
Pepsin. . .
Rennet. . .
Pepsin . . .

6.47
6.69
7.13
7.58

8.37

9.00

10.16

10.25

3.21
3.74
5.54
4.02

5.13
3.57
8.11
8.91

An examination of this table shows that there is a
very fair parallel in the digesting action of rennet-
extract and commercial pepsin. Thus, the action in-
creases when acid is added; the increase of soluble
proteins is largely confined to caseoses and peptones ;
the amount of amino acids remains practically
unchanged; no ammonia is formed. The results

CAUSES OF RIPENING CHANGES

36:

indicate that the action of pepsin was able to
account for all the changes observed in the case of
rennet-extract in the presence of acid. But an inter-
esting difference is observable in connection with the
results when no acid was present. We notice that,
in the absence of acid, there is a gradual increase of
soluble compounds in the case of rennet-extract from
9.98 to 18.00 at the end of 9 months, but no such
increase is seen with the commercial pepsin. This
difference suggests that the rennet-extract contained,
in addition to the peptic ferment proper, a digesting
enzym not contained in the comimercial pepsin ; this
enzym shows the ability to dissolve insoluble protein
even in the absence of acid. This observation has
been confirmed by the work of others.

The effect of commercial pepsin in increasing in
cheese the amount of water-soluble proteins, when

EFFECT OF COMMERCIAL PEPSIN IN

CHEESE-RIPENING

Nitrogen, expressed ;

IS percentage of nitrogen

in cheese, in

"orm of:

Age of

No. of

cheese

Form of

experi-

when

Enzyms

Water-

Para-

ment

ana-

added

soluble

nuclein ,

lyzed

proteins
and de-
rivatives

Brine-
soluble

caseoses
and pep-
tones

Amino
acids

Ammo'
nia

Per cent

Perct.

Fresh

Rennet-

extract

4.76

65.45

2.41

2.36

6 months

28.37

17.14

15.87

6.35

2.00

Fresh

Rennet
andl gm.

6.97

36.76

4.11

2.86

6 months

pepsin

29.80

17.04

16.47

7.10

1.91

Fresh

Rennet
& 15 gm.

25.00

59.53

22.80

2.20

3 months

pepsin

46.67

11.61

41.00

5.68

0.49

366 SCIENCE AND PRACTICE OF CHEESE-MAKING

used in increasing amounts, is shown by the results
given on page 365, which were obtained in an experi-
ment in which the cheese was made in an entirely
normal way, except that hydrochloric acid was used
in place of lactic acid or a "starter."

The following tables are taken from the records of
the Wisconsin experiment station:

DIGESTING ACTION OF DIFFERENT AMOUNTS OF RENNET-
EXTRACT IN CHEESE

Amount of

Age of

cheese

when

analyzed

Percentage of nitrogen in form of:

rennet-
extract
used

Water soluble

proteins and

derivatives

Caseoses and
peptones

Amino
acids

Ounces
3
12
24

3
12
24

Months
1
1
1

3
3
3

13.80
18.85
24.83

23.33
31.93
34.54

10.18
15.17
21.06

11.77
20.18
22.80

3.62
3.68
3.77

11.56

11.75
11.74

DIGESTING ACTION OF RENNET-EXTRACT AND PEPSIN

IN CHEESE

Cheese made
with larcre

Age of

cheese

when

analyzed

Percentage of nitrogen in form of:

amount of

rennet and

with rennet

plus pepsin

Water-soluble

proteins and

derivatives

Caseoses and
peptones

Amino
acids

Normal cheese

and pepsin . .

70 days
70 days

26.67
37.47

14.57
25.07

12.10
12.40

We may summarize as follows the results estab-
lished by investigation regarding the relation of ren-
net-extract to the cheese-ripening process :

CAUSES OF RIPENING CHANGES 367

(i) Rennet-extract contains an enzym which has
the power of digesting or dissolving the insoluble
protein in cheese.

(2) Such digesting action by rennet-extract does
not take place in cheese which has been made without
any acid or acid salt in the milk and curd.

(3) The digestive action of the enzym contained
in rennet-extract exerts its digesting power only in
the presence of acids or acid salts. In the case of
normal cheese, the acid formed in the cheese-making
process is lactic acid, which, however, does not act
as free acid, since it reacts with calcium salts, form-
ing neutral calcium lactate and calcium acid phosphate
and, probably, citrate. The acid salts enable the ren-
net-enzym to exert its digesting power. The same
general result may be accomplished by adding a free
acid or an acid salt to milk during the cheese-making
process.

(4) The extent to which the digesting enzym of
rennet-extract can act depends largely upon the degree
of acidity developed in the cheese-making process. It
is probable that no action begins until the equivalent
of 0.30 per cent of lactic acid has been formed.

(5) The products formed by rennet digestion of
cheese proteins are largely confined to the bodies
known as caseoses and peptones, only small
amounts of amino acids being formed and little or
no ammonia.

(6) Increased use of rennet-extract in cheese-
making results in a more rapid formation of water-
soluble protein compounds. This is not due, as some
formerly thought, to an increased amount of water in
cheese, which was supposed to be a necessary result

368 SCIENCE AND PRACTICE OF CHEESE-MAKIKG

of using larger amounts of rennet-extract. Increased
amounts of whey in cheese may, if not too excessive,
favor more rapid action of the peptic ferment in
rennet, because increase of whey in cheese means
increase of milk-sugar and this means more lactic
acid.

(7) Commercial pepsin, when used in milk and
cheese, behaves in a manner closely resembling
rennet-extract; since it acts only in the presence of
some acid or acid salt and forms relatively small
amounts of amino acids as compared with caseoses
and pept'oaes.

(8) Rennet-extract, therefore, contains an enzym
w^hich has the power of performing the same kind and
amount of digesting work in cheese-ripening as pepsin.

(9) Rennet-extract appears to contain, in addi-
tion to the peptic ferment, another ferment which
has the power to digest milk-casein to some extent in

the absence of acids or acid salts.

ACTION OF GALACTASE IN CHEESE-
RIPENING t

The main characteristics of the milk-enzym, galac-
tase, have been discussed already (p. 297). It has
been shown that galactase prepared from separator-
slime in the manner described by Babcock and Rus-
sell contains, at least, two other enzyms. But we are
not particularly interested to know in this discussion
whether galactase is one or two or more enzyms;
the point of importance here is that milk contains a
substance which has the power under certain condi-
tions of converting milk-casein and the paracasein
of cheese-curd into soluble forms of proteins and

PAUSES OF RIPENING CHANGES 369

protein derivatives. The fact, first discovered by
Babcock and Russell, that there is such an enzym
has been abundantly confirmed by work done at
the New York experiment station and elsewhere.
The work done^ by the discoverers in "studying the
properties of galactase led them to regard as one
of the distinguishing characteristics of this enzym
its ability to convert casein and paracasein into
sim,pler proteins and protein derivatives, finally
forming ammonia. On the basis of this property,
the conclusion was reached by them that galactase
is the chief agent in the ripening of cheddar cheese.
Work done at the New York experiment station
failed to confirm the conclusion that galactase
could form ammonia in the case of either milk or
cheese. In carrying on the work in New York,
cheese was made from milk to which chloroform had
been added and the cheese was kept in an atmosphere
of chloroform, in order to prevent the action of micro-
organisms. The only ripening agents present were,
therefore, galactase and the enzym or enzyms of
rennet. Cheese, thus made and kept, has de-
veloped no ammonia, or possibly slight traces only,
even after 24 months. The data on the next page
illustrate this fact.

Stated in a general way, these results show that ( i )
in cheese made and ripened in the presence of chloro-
form, the amount of caseoses and peptones is largely in
excess of the amount of amino acids; (2) the reverse
is true in normal cheese; (3) that ammonia appears
in normal cheese much earlier and in larger amounts
than in chloroformed cheese, appearing in the latter
only after 12 months. About as much ammonia ap-
peared in the normal cheese in I month as appeared in

370 SCIENCE AND PRACTICE OF CHEESE-MAKING

the chloroformed cheese in 2 years. The amount of
amino acids formed in the chloroformed cheese in 2
years was about equal to the amount formed in the
normal cheese at 5^ months.

From these results, it is seen that, in a normal
cheese, the amino acids continuously increase, while

DIFFERENCE IN CHARACTER OF CHEMICAL CHANGES IN
NORMAL AND IN CHLOROFORMED CHEESE

Percentage of nitrogen in

form of:

Character of

cheese

Age

Water-soluble

Caseoses

Amino

Ratio

proteins and

and pep-

acids

Ammo-

derivatives

tones

(1) to (2)

nia

Months

(1)

(2)

Normal cheese

16.70

2.95

5.42

1: 1.80

0.86

Chloro'^orm "

8.73

3.71

0.86

1:0.23

.00

Normal "

■ 20.30

2.51

8.49

1:3.40

1.29

Chlorofonn '

12.00

7.31

1.82

1:0.25

0.00

Normal "

29.80

5.37

12.60

1:2.40

2.51

Chloroform "

17.50

10.20

3.22

1:0.31

0.00

Normal "

34.60

4.97

18.50

1:3.70

3.38

Chloroform "

22.30

12.40

4.73

1:0.39

0.00

Normal "

36.10

3.08

20.10

1:6.50

4.42

Chloroform "

24.00

10.90

8.11

1:0.74

0.00

Normal

37.85

2.70

23.50

1:8.70

4.87

Chloroform

29.50

12.52

11.60

1:0.93

0.00

Normal

42.30

3.03

24.87

1:8.22

5.69

Chloroform '"

34.70

11.89

15.77

1: 1.33

0.35

Normal "

45.10

4.47

27.43

1:6.14

6.04

Chloroform "

37.40

15.68

14.41

1:0.92

0.98

Normal "

46.07

2.44

30.97

1: 1.27

5.45

Chloroform "

37.05

10.60

21.06

1:2.00

, ,

Chloroform "

40.26

21.82

18.45

1:0.84

1.04

the caseoses and peptones increase for some months
and then decrease. In a chloroformed cheese, the dif-
ferent classes of compounds under discussion all in-
crease continuously from the beginning for two
years and more. In normal cheese, traces of am-
monia appear at an early stage of ripening, while, in
chloroformed cheese, the first traces usually appear

CAUSES OF RIPENING CHANGES 37I

only after the lapse of about one year, and the increase
is so very slow, that even after two years, only minute
amounts are present. From these results, it apfpears
that while galactase performs important work in the
ripening of cheese, it cannot be the chief factor in this
process, because its action produces amino acids only
very slowly, and ammonia practically not at all within
the normal lifetime of cheddar cheese.

One of the properties of galactase is its sensitive-
ness to acids. In milk containing 0.15 per cent of
hydrochloric acid, the galactase is much less active
than in milk containing less acid. In the work done
at the New York experiment station, the addition of
as much as 0.2 per cent of acid materially increased
the amount of soluble protein compounds in cheese.
Thus, cheese made with no acid had not ripened at all
in 3 months, while cheese made with acid under con-
ditions otherwise the same, contained 32.37 per cent
of its nitrogen in soluble form in 3 months. This fact
also is not consistent with the belief that galactase
is the chief agency in the process of cheese-ripening.

ACTION OF MICRO-ORGANISMS IN
CHEESE-RIPENING

We come now to a consideration of the fourth and
last agency which has been assigned as one of the
causes of the chemical changes in the ripening of ched-
dar cheese, micro-organisms. Although we discuss
this subject last, it was, in point of time, the first to
be studied. When the subject of cheese-ripening was
first taken up for serious study, it was thought that
the whole process was due to the action of bacteria,
and all efforts were confined to this single line of

2^72 SCIENCE AND PRACTICE OF CHEESE-MAKING

investigation for years, to the neglect of all other
possibilities. The general statement of this theory is
that the changes observed in proteins during the
cheese-ripening process are caused by the direct action
of micro-organisms. This has appeared in many dif-
ferent forms according to the particular kind of micro-
organisms to which the work was attributed. Of the
different micro-organisms assigned as the cause of
cheese-ripening, we can mention only one, the lactic
acid organisms. Freudenreich has been the most
prominent champion of this explanation of the
changes in cheese-ripening, and he devoted years
of investigation to the lactic acid organisms. In
favor of this particular theory, we have the fol-
lowing facts: (i) The lactic acid species of bacteria
are abundant from the start and increase in num-
bers enormously for some time, suppressing the
growth of those bacteria that are known to have
the power of transforming milk-casein and the
paracasein of cheese-curd into soluble products.
(2) There is a coincidence in time between the
early marked advance in the formation of soluble
proteins and the period of bacterial increase. Against
this theory we have the following facts : ( i ) The
lactic acid bacteria that are most useful in cheese-
making have not been satisfactorily shown to have
the power of changing milk-casein or paracasein into
soluble products. (2) Ammonia is found at an early
stage of cheese-ripening, but it has not been proved
that lactic acid organisms produce ammonia. (3) A
large proportion of the chemical changes in cheese
proteins appear after the lactic acid bacteria have
greatly decreased in number. This has been explained
by saying that the bacteria secrete an enzym which

CAUSES OF RIPENING CHANGES 373

digests cheese proteins, and this continues the work
long- after the bacteria themselves disappear. The
existence of such enzyms from such a source has not
been satisfactorily proved yet. The weight of evi-
dence up to the present time appears to indicate that
the chief, if not the only, work of the lactic acid bac-
teria is completed when milk-sugar has been changed
into lactic acid.

We may ask here. What justification have we for
the germ theory in general? (i) It has been shown
that various germs found in cheese have the power
to cause in milk-casein and paracasein changes much
like those observed in cheese. (2) Cheese-curd,
treated with germicides, fails to ripen. (3) Milk,
sterilized and made into sterile cheese, does not ripen.
Apparently, there is no ripening, at least nothing
like complete ripening, when there are no micro-
organisms in cheese. The relations of certain
micro-organisms to certain kinds of cheese, espe-
cially of the soft type, have been satisfactorily worked
out, but the relations to hard types of cheese,
like the cheddar, are far from being satisfactorily
known. "

In going over the results of investigations that bear
on the subject of cheddar cheese-ripening, we have
seen (i) that lactic acid bacteria do an important and
necessary work in changing milk-sugar into lactic
acid, which reacts with calcium salts in the milk, form-
ing neutral calcium lactate and acid calcium phos-
phate. (2) We have seen that, in the presence of the
acid medium thus furnished by the action of lactic acid
bacteria, the peptic enzym contained in rennet is able
to bring about quite extensive chemical changes in the
protein of the curd or green cheese, forming such

374 SCIENCE AND PRACTICE OF CHEESE-MAKING

compounds as paranuclein, caseoses and peptones and
much smaller proportions of amino acids and little or
no ammonia. (3) Galactase is able to perform chem-
ical work similar in character to that of rennet-pepsin,
but how much insoluble protein it can render soluble
in a given period of time, we do not know. (4)
None of the three agencies previously mentioned has
the power of forming ammonia, as found in normal
cheese-ripening. It, therefore, appears that bacteria
alone must be responsible for the production of am-
monia and of a large proportion of the amino acids.

It is obvious that the process of cheese-ripening is
not as simple as was once believed, but, on the con-
trary, is exceedingly complex. We cannot say yet
just what part each agent plays nor to what extent
each is independent of, or dependent upon, the others.
For example, the digesting action of rennet is clearly
dependent upon acidity. Does the action of rennet
have anything to do with the changing of the in-
soluble curd into a brine-soluble substance and back
again into a substance insoluble in brine? Or are
these changes immediately dependent upon acid-form-
ing bacteria? Does the rennet have any digesting
effect until the brine-insoluble form of protein ap-
pears? What forms of cheese proteins can galactase
or other milk enzyms attack and under what condi-
tions of acidity, temperature, etc.? When do the
bacteria begin their work in rendering soluble the
insoluble cheese proteins? Or do they act only upon
the products formed by rennet or galactase? Is the
bacterial work confined to one specific micro-organism,
or is the work associative?

We thus see that there are many details still un-
settled ; but, in view of what we think we know now,

CAUSES OF RIPENING CHANGES 375

we are justified in believing that the chemical changes
of cheese-ripening are the result of several different
kinds of fermentative agents, the precise relations of
each of which to the details of the ripening process
have not been satisfactorily worked out yet.

CHEESE FLAVORS

In connection with the ripening of cheese, the ques-
tion of cheese flavor is, of course, one of paramount
importance. What do we know about the origin of
cheese flavor, the particular substance or compound
that the flavor comes from, and the method of its
formation? Very little, in detail. When we speak
or think of flavors in cheese, we too commonly view
them in a vague, misty and mysterious way. As a
matter of fact, flavors are realities, and sometimes
very striking ones, and they come from real things.
Every flavor represents one or more specific chemical
compounds. Some one chemical compound, or, it
may be, some mixture of two or more definite
chemical compounds, is entirely responsible for
each and every flavor found in cheese, or, for that
matter, anywhere else, whether pleasant or other-
wise.

The study of the problem of cheese flavors has
received less attention than that of the chemical
changes in cheese proteins, though the two questions
are probably closely related. The questions that
present themselves in connection with the normal
flavors of American cheddar cheese are: (i) What
are they? (2) Where do they come from? (3)
What produces them or what is the manner of their
formation ?

376 SCIENCE AND PRACTICE OF CHEESE-MAKING

The following facts have some bearing on these
questions :

(i) Newly made cheese has no real cheese flavor.

(2) Some days or weeks must pass before real
cheese flavor begins to appear.

(3) The breaking down of the proteins contained
in the cheese-curd and green cheese, resulting in the
formation of water-soluble protein derivatives, pre-
cedes, to some extent, the appearance of flavor in
cheese.

(4) Cheese flavors are produced by some chemical
change in some compound or compounds present in
green cheese.

(5) In experiments where bacterial action is pre-
vented, we do not find cheese flavor.

(6) Neither galactase nor rennet nor pepsin ap-
pears to be able to produce compounds that have any
flavor at all.

(7) Flavor develops more quickly at higher than
at lower temperatures.

(8) Flavor develops more rapidly in a moist than
in a dry cheese.

(9) Many of the abnormal flavors of cheese can
be traced directly to specific micro-organisms. For
example, the ofifensive odor, usually characterized as
"taint," is traced to a gas-producing organism closely
related to Bacillus coli communis, a species of bacteria
commonly found in the intestinal tract.

(10) Bitter flavor in cheese has been identified
as a compound formed from acetaldehyd (produced
by the alcoholic fermentation of milk-sugar) and am-
monia, the product of bacterial action.

CAUSES OF RIPENING CHANGES 377

(11) The flavoring substance, whatever it is, is
present in extremely small amounts

(12) A cheesy flavor often develops in butter that
is not kept at sufficiently low temperature. A distinct
cheesy flavor is common in kumiss, when it is one o'-
two weeks old.

What suggestions can we derive from the preceding-
statements ?

(i) It is quite possible that the particular com-
pounds which furnish cheese flavor are certain pro-
tein derivatives that are formed only after the lapse
of some time and are much simpler than the principal
protein found in the green cheese. This suggestion is
supported by certain facts, (a) Cheese flavors do
not appear until these simpler compounds begin to
be formed, (b) Such compounds are known to be
capable of furnishing flavors, (c) Extremely minute
quantities of such substances go a long way in pro-
viding flavor. Owing to the extremely minute quan-
tities of such compounds present, the problem of
isolating and identifying them is one of great diffi-
culty.

(2) We find that, in cheese cured at low tempera-
tures, we have, in general, about the same kinds of
compounds as in cheese cured at higher temperatures,
but the chemical changes have not gone quite so fast
and we have smaller quantities of these compounds
formed that produce flavor. This is in full agreement
with the characteristic mild flavor of cold-ripened
cheese.

(3) In old cheese, characterized by very strong
flavor, especially a pungent odor and biting taste,
ammonia is always present in large quantities as com-

;^y8 SCIENCE and practice of cheese-making

pared with mild-flavored cheese. The pungent flavors
are due to ammonia compounds.

(4) As to the material source of flavoring com-
pounds in cheese, it is quite probable that they come
from the changing of paracasein into simpler com-
pounds, especially such compounds as amino acids and
ammonia.

(5) Fat was formerly regarded as the sole source
of flavor in cheese, and in butter also. It is true that
when fat in cheese decomposes, it may form a variety
of flavoring substances, such, for example, as butyric
acid, the characteristic flavor of rancid cheese and
butter; but such flavors are offensive. Fat in ched-
dar cheese does not appear to undergo any appreciable
change in the early stages of cheese-ripening, espe-
cially when cheese is ripened under proper conditions
of temperature. The decomposition of fat which gives
rise to the small white specks sometimes observed in
cheese ripened at low temperature does not affect the
flavor in any way.

(6) What is the probable cause of formation of
cheese-flavoring compounds? It is well-known that
the action of certain bacteria is responsible for many
of the bad flavors of cheese. Up to the present time,
we are unable to find any satisfactory cause other than
micro-organisms for the real, desirable cheese flavor;
because, in the absence of living organisms or of the
enzyms secreted by them, we get no flavor.

CHAPTER XXVI

Commercial Relations of Cheese-Ripening

In the three chapters preceding, we have considered
cheese-ripening in relation to (i) the conditions that
affect the loss of weight during the ripening process,
(2) the chemical changes taking place, and (3) the
causes of the changes that occur in the process. In-
cidentally, we have touched upon some of the practical
relations of the results, but have reserved for a
separate chapter a more detailed discussion of the
commercial aspects of cheese-ripening. We propose
now to take up for more extended treatment some
of the practical applications of the results of investiga-
tion and shall consider the following subjects: (i)
Extent of ripening losses at cheese-factories, (2)
value of water in cheese to dairymen, (3) moisture
in cheese in relation to commercial quality, (4) the
proper percentage of moisture in cheese, (5) value of
water in cheese to consumers, (6) the reduction
of ripening losses in commercial investigations, (7)
the relation of conditions of ripening to the quality
of cheese, (8) the effects of freezing on quality of
cheese, (9) financial application of results of cheese-
ripening investigations.

FACTORY LOSSES IN RIPENING

From inquiries made among cheese-makers several
years ago, we found quite a variation in respect to
the loss of moisture experienced by them in ripening

379

380 SCIENCE AND PRACTICE OF CHEESE-MAKING

cheese. One of the most complete records, covering
an entire season, furnished by a cheese-maker and
factory owner who has better than average conditions
in his curing-rooms, made the average loss of weight
during 30 days amount to about 5 oounds per 100
pounds of cheese. Others reported an average loss
for the first 30 days as high as 10 pounds per 100
pounds of cheese. The average loss was somewhere
between these two extremes, probably not far from 7
pounds per 100 pounds of cheese. In many fac-
tories, conditions have not improved since the
inquiry was made.

VALUE OF WATER IN CHEESE TO DAIRY-
MEN

To the cheese-maker and producer of milk, water
in cheese is money when put there in the right way
and in the proper proportions. It is essential, in the
process of manufacture, to incorporate water in cheese
in quantities best suited to the requirement of the
market for which the cheese is intended, and then it
is equally essential that the water be kept there with
the least possible loss. From the dairymen's stand-
point, it is desirable to sell as much water in cheese
as will suit the consumer. In preventing excessive
loss of moisture, there is more water to sell at cheese
prices, and at the same time a resulting product that
suits the consumer better. In the conditions prevail-
ing in many factories, high temperatures which cause
increased loss of moisture also cause loss of fat by
exudation from the surface of the cheese. At 75° F.
and above, this loss becomes considerable. It has been
shown that the loss of moisture in curing-rooms can

COMMERCIAL CHEESE-RIPENING 381

be reduced to 4 pounds per 100 pounds of cheese under
conditions practicable at factories. Using this figure
as a basis for calculation, we find that, for every loc
pounds of cheese, an average of 3 pounds of water
could be saved to sell at cheese prices. This would
mean an average increase of 30 cents, received for
every 100 pounds of cheese. This would mean an
average saving of $300 a season for a factory with
a total season's output of 100,000 pounds of cheese.
One cheese-maker reports that he calculated one sea-
son's loss from shrinkage and found it over $600.
While such losses may not be regarded as large in
comparison with the total receipts, they constitute a
noticeable percentage when viewed as unnecessary
decrease of profits, and are well worth saving.

MOISTURE IN CHEESE IN RELATION TO
COMMERCIAL QUALITY

We have just called attention to increased re-
ceipts coming from cheese, as a result of preventing
excessive loss of moisture. Such saving of moisture
not only increases the amount of cheese to be sold
but also increases the value of the cheese from the
standpoint of commercial quality.

The relations existing between moisture and flavor
are known only in a very general way. But we know
something of the general relation between moisture
and texture. Excessive moisture produces a degree
of softness, which is undesirable, from a commercial
standpoint, and at ordinary temperatures favors the
formation of holes, a serious fault in the texture of
cheddar cheese intended for export trade. On the
other hand, deficient moisture favors the production

382 SCIENCE AND PRACTICE OF CHEESE-MAKING

of a crumbly, dry, mealy body, which is an undesir-
able condition. High temperatures cause excessive
loss of moisture and result in the production of
a crumbly body. This condition injures the commer-
cial quality of cheese and results in lower prices for
such cheese. The following table illustrates, in a
practical way, the effect of different temperatures
upon texture and moisture:

EFFECT OF TEMPERATURE OF CURING ON TEXTURE AND

MOISTURE OF CHEESE

Temperature of

Texture of cheese

Moisture lost by 100

cunng-room

(Perfect texture is 25)

pounds of cheese

Lbs.

55°F.

24.6

8.5

60°F.

24.4

9.0

6S°F.

23.6

9.2

70°F.

22.0

10.2

7S°F.

21.4

10.7

80°F.

20.6

13.1

WHAT PERCENTAGE OF MOISTURE
SHOULD CHEESE HAVE?

Much of the cheese made in New York contains,
in the fresh state, from 36 to 37.5 per cent of water.
The home-trade cheese, much of which is made in the
fall, contains 38 to 40 per cent of water. For the
average consumer, it is safe to say, the amount of
moisture in cheese should be not less than 33 to 35
per cent at the time of consumption. Taking every-
thing into consideration, it is reasonable to expect
better results in reference to quality by holding a
moderate amount of moisture in the green cheese and
so ripening as to lose only a small amount of water.

COMMERCIAL CHEESE-RIPENING 383

than by holding an excessive amount of moisture in
the green cheese and so ripening as to lose a larger
amount of moisture. Some cheese-makers expect that
they must lose lo pounds of weight per lOO pounds
of cheese in ripening, and they attempt to meet this
loss by retaining 40 per cent or more of moisture in
the cheese. Such a practice cannot lead to good re-
sults from any point of view.

A fact that should not be lost sight of in this con-
nection is this: Cheese ripened at such low tempera-
tures as are favorable to diminishing the loss of
moisture can carry larger amounts of moisture from
the start without impairing the quality

VALUE OF WATER IN CHEESE TO

CONSUMERS

In the first place, cheese that has not lost too much
of its moisture is more pleasing to the taste of the
average consumer. In the next place, the more com-
pletely a cheese dries out, the harder and thicker is
the rind and the greater the loss to the consumer.
Most people have become accustomed to such a waste,
but much of it is unnecessary. In a carefully ripened
cheese, the rind is comparatively moist and only a very
thin portion need be lost, and even this can be used
in cooking.

REDUCTION OF RIPENING LOSSES IN
COMMERCIAL INVESTIGATIONS

In 1902-3 an investigation, on a commercial scale,
was undertaken by the Dairy Division of the Bureau
of Animal Industry, United States Department of

384 SCIENCE AND PRACTICE OF CHEESE-MAKING

Agriculture, in co-operation with the experiment sta-
tions of Wisconsin and New York, in which cheese
was ripened at 40°, 50° and 60° F., some being cov-
ered with paraffin. In 1903-4 the Dairy Division

FIG. 47 — A week's temperature record of a curing-room

HELD AT 50°F

repeated the work, but used a lower range of
temperatures, 28°, 34° and 40° F., and, in one case,
5° F. The object of these investigations was to
study on a commercial scale, under commercial con-
ditions, (i) the influence which different tempera-
tures have upon (a) the loss of weight in cheese, and

^■pya„Sf^

fJMSUdL

D£C. 19
DEC 26

(b) the
of the
different

FIG. 48--TEMPERATURE
RECORD COVERING SEV-
ERAL MONTHS IN CASE
OF CURING - ROOMS
HELD AT 28° AND
40° F.

(b) the commercial qualities of
the cheese; and (2) the in-
fluence of covering cheese with
paraffin upon (a) the loss of
weight in cheese, and
commercial qualities
cheese, when kept at
temperatures.

In the different sets of ex-
periments, the cheeses used
were of the following sizes :
(l) Cheddars, 65-70 pounds; (2)
Cheddars, 40-45 pounds; (3)
Flats or Twins, 30-35 pounds;
(4) Daisies, 20 pounds; (5)
Young Americas, 10 to I2>^
pounds; (6) Prints, 10 pounds.

The experiments were be-
gun in October and extended
through periods of time lasting
20 to 35 weeks. The cheeses
were obtained direct from fac-
tories in New York, Pennsyl-
vania, Ohio, Michigan, Illi-
nois, Wisconsin and Iowa,
were 10 to 15 days old
placed in storage. In
cases they represented
Cheddar type manufactured for
export trade, close-textured,
firm-bodied and long-keeping.
In some cases the Michigan
type was used, which is char-
acterized as soft-bodied, of high
water content, more or less

385

They

when

most

the

386 SCIENCE AND PRACTICE OF CHEESE-MAKING

porous and poor in keeping quality. Another type
represented was the sweet-curd, more or less inter-
mediate in qualities between the cheddar and the
Michigan home-trade types.

The cheeses were placed in storage during the ex-
periments where the temperature could be very closely
kept under control. Various devices and records are
in use for ascertaining the uniformity of the tempera-
ture from day to day. Two different forms of records
are given in Figs. 47 and 48.

It is not practicable to present the detailed results
of the different experiments; we must limit our con-
sideration to a general summary of the results. We
shall present the results relating to the losses of ripen-
ing under the following subdivisions : ( i ) Tempera-
ture, (2) size of cheese, (3) type of cheese, and (4)
coating with paraffin.

Influence of temperature on loss of weight. — The
results of the various investigations agree in the fol-
lowing respects : ( i ) The cheese continued to lose
weight in nearly every case as long as weighings were
made (about 250 days), this being true at all tem-
peratures employed (28° -60° F.). (2) The loss of
weight was least at the lowest temperature (28° F.)
and increased with rise of temperature. This can be
illustrated in case of the 65-70-pound cheddars, as
follows :

POUNDS OF WEIGHT LOST FOR TOO POUNDS OF CHEESE

STORED AT

27 weeks
35 weeks

28°F.

34°F.

40°F.

SO°F.

1.81

4.18

4.68

6.00

2.88

5.12

5.87

60°P.
9.90

COMMERCIAL CHEESE-RIPENING

387

At the end of 2y weeks, the loss of weight was more
than 3 times as great at 40° F. as at 28° F., and about
5 times as great at 60° F. as at 28° F. At the end of
35 weeks, the loss at 40° F. was just twice as great as
at 28° F.

Influence of size of cheese in loss of weight. —
Small-sized cheeses, other conditions being the same,
lost a larger amount of moisture than large cheeses.
This tendency is shown at different temperatures by
the following tabulated statement:

WEIGHT LOST PER lOO POUNDS OF CHEESE IN 20 WEEKS

Average weight
of cheese

At 40°F.

At 50°F.

At 60°F.

Pounds
70
45
35
12i

Pounds
2.5
2.7
3.9
4.6

Pounds
2.4
3.7
5.9
8.1

Pounds

4.2

5.1

8.5

12.0

The variation in loss between different sizes is much
less at lower than at higher temperature.

Influence of type of cheese on loss of weight. —
Firm-bodied, close-textured cheese loses water less
rapidly than soft-bodied, open-textured cheese (p. 324).

Influence of paraffin coating on loss of weight. —
Cheese covered with paraffin loses less weight than
cheese not so coated. By covering cheese with
paraffin, a saving in loss of weight can be effected
amounting to 5 or 6 pounds per 100 pounds of cheese
at 60° F. ; and at 50° F. or below the total loss of
weight can be reduced to i or 2 pounds per 100
pounds of cheese in the ordinary period of ripening.
At 40° F., the loss in case of the large-sized ched-
dar was reduced about one-half, as compared with

^88 SCIENCE AND PRACTICE OF CHEESE-MAKING

cheese not coated; at 34° F., nearly three-fourths of
the loss was prevented; at 28° F., the losses were
very slight, only a little over ^ pound in 27 weeks.
The use of paraffin coating makes a greater propor-
tionate saving in small cheeses than in large ones. In
the case of the Young America cheeses, the loss at
40° F. was reduced to about one-fourth of what it
was when the cheese was uncoated

RELATIONS OF CONDITIONS OF RIPENING
TO QUALITY OF CHEESE

In all the experiments mentioned, carefully selected
experts judged the cheese from a commercial stand-
point and scored them. These examinations were
made at regular intervals during the continuation of
the experiments. The results will be considered with
reference to the effect of (i) temperature, (2) coat-
ing with paraffin.

Influence of temperature on quality. — Below 40°
F., and down to 28° F., the temperature does not
appear to have any marked effect upon the commercial
quality of cheese. Cheese ripened at 40° was superior,
almost without exception, to cheese ripened at higher
temperatures. The following figures show the aver-
age scores at different temperatures:

Temperature

40°F. . .

Score
95.7

50°F

94.2

60°F

91.7

There was more marked deterioration in quality
between 50° and 60° F. than between 40° and 50° F.
In general, the higher the temperature, the greater is

COMMERCIAL CHEESE-RIPENING

389

the relative deterioration of cheese in quahty for each
degree of temperature.

The following figures demonstrate that the dif-
ference in quality falls mostly on the flavor (50,
perfect), and to a less extent on texture and body
(25, perfect) :

Qualities

At 40°F.

At 50°F.

At 60°F.

Flavor

47.4
23.4

46.4
23.0

44.8

Bodv and texture

22.2

At any given time, the cheese ripened at 40° F. was
usually better in quality than that at 50° F., and that
at 50° F. was better than that at 60° F. The longer
the time of ripening, the greater was the difference in
favor of the lower temperatures, as illustrated in the
following table:

Age of cheese

Score at 40°F.

Score at 50°F.

Score at 60°F.

Weeks
10
20
28
35

96.3
93.8
94.2
95.3

94.7
91.5
91.9

• • •

92.
89.7

■ • •

• • •

The cheese cured at 60° F. showed such deteriora-
tion of quality in 20 weeks that it was sold in order
to prevent complete loss.

Influence of paraffin coating on quality. — The

effect of covering cheese with paraffin was, in several
cases, to improve the quality of the cheese so covered.
The difference was more marked at 60° F. than at
lower temperatures. The cheese coated with paraffin

390 SCIENCE AND PRACTICE OF CHEESE-MAKING

and ripened at 40° gave its highest score at the end
of 35 weeks. In no case did the cheese coated with
paraffin show any depreciation in quahty as compared
with cheese not so covered. These results are in har-
mony with what one might reasonably predict. Any
condition which maintains in the cheese the uniformity
of the moisture, when not in excess, favors the. normal
ripening changes.

The finish of cheese was greatly improved by a
coating of paraffin, since the growth of molds is pre-
vented. In every case cheeses covered with paraffin
were entirely clean, while the others were more or
less heavily coated with molds.

fJS^y*^ ■^^!^B^5J!y^l^^W5,g)-.^,.^

'iarl^-Anjir ifl* j^ UrW^j»^:^3i_'! :

FIG. 49 — SECTION OF FROZEN CHED-
DAR CHEESE AFTER STORAGE 5j^
MONTHS AT 5° F.

THE EFFECTS OF FREEZING ON QUALITY

OF CHEESE

Cheese placed in a room kept at 5° F. was im-
mediately frozen hard. After a time the ends and
sides appeared to be lumpy, due to the expansion of
the frozen water in the cheese. After being 6 months
in a frozen condition, the cheese was slowly thawed

COMMERCIAL CHEESE-RIPENING

391

and examined. When freshly cut, the appearance was
normal, but the surface dried out more rapidly than
in normal cheddar cheese. The body was crumbly, as
in the case of a cheese deficient in water. Little or no
ripening had taken place and such insipid flavor as
there was did not resemble anything normal. The
frozen cheese also showed a mottled appearance, nc t
shown by any other cheese ripened at 28° F. or above.
Fig. 49 shows the appearance of a cheese after being
kept at 5° F. for several months.

FINANCIAL APPLICATION OF RESULTS
OF CHEESE-RIPENING INVESTIGATIONS

Any reduction in loss of weight or any improve-
ment in quality in cheese-ripening means an increase
of money that can be realized in the sale of cheese.
We have seen that the curing of cheese at tempera-
tures as low as 40° F. has the effect of ( i ) preventing
loss of moisture and (2) increasing the value of the
cheese. Therefore, we not only have more cheese to
sell but can sell it at a higher price. Taking cheese
20 weeks old as a basis for comparison, we know how
much weight is lost at different temperatures and also
the difference in price. From these figures the fol-
lowing tabulated statement is given :

MONEY RETURNS AT SEVERAL TEMPERATURES

Temperature
of curing

Cured cheese

equivalent to 100

pounds of green

cheese

Market price of 1
pound of cheese

Receipts from
cheese

Degrees F.
40
50
60

Pounds
96.2
95.2
92.2

Cents
13.275
13.050
12.675

Dollars
12.77
12.42
11.69

392 SCIENCE AND PRACTICE OF CHEESE-MAKING

These figures indicate that from lOO pounds of green
cheese put into the curing-room we were able to re-
ahze from that cured at 40° F., 35 cents more than
from cheese cured at 50° F., and $1.08 more than from
that cured at 60° F. From the cheese cured at 50°
F., we received y^i cents more for 100 pounds than
from that cured at 60° F.

If we compare our results obtained with cheese cov-
ered with paraffin with those given by cheese not so
covered, we have the following tabulated statement:

COMPARATIVE VALUE OF PARAFFINED AND UNPARAF-

FINED CHEESE

Tempei^
ature of
curing-
room

Cured cheese

equivalent to 100

pounds of green

cheese

^Value of 1 pound
of cheese

Receipts from
cheese

Paraf-
fined

Not par-
affined

Paraf-
fined

Not par-
affined

Paraf-
fined

Not par-
affined

Deg. F.
40
50
60

Pounds
99.7
99.5
98.6

Pounds
96.2
95.2
92.2

Cents
14.25
14.25
13.75

Cents
14.25
14.25
13.50

Dollars
14.21
14.19
13.56

Dollars
13.70
13.56
12.45

At 40° F, the difiference in favor of the paraffined
cheese is 51 cents for 100 pounds of cheese originally
placed in the curing-room; at 50° F. the difference
is 63 cents, and at 60° F., $1.11. Covering cheese
with paraffin results in greater saving at higher tem-
peratures than at lower temperatures.

Comparing paraffined cheese cured at 40° F. with
unparaffined cheese cured at 60° F., we find a differ-
ence of $1.76 for 100 pounds of cheese in favor of
the paraffined cheese and the lower temperature.

COMMERCIAL CHEESE-RIPENING 393

These experiments demonstrate that, by curing
cheese at lower temperatures than those that have
been commonly in use, it is possible to obtain a perfect,
edible quality of cheddar cheese, which means cheese
of clean, mild, delicate flavor, somewhat lasting, but
not so sharp as to bite the tongue ; and body such
that a piece of cheese on the tongue dissolves com-
pletely, leaving only a sensation of smoothness and
richness, with no trace of harshness or grittiness.
Such cheese can be eaten without the disagreeable
effect of long after-tasting, which imperfectly cured
cheese produces. The consumption of cheese can be
greatly stimulated by making the cheese right and
then ripening it under proper conditions of tempera-
ture and moisture.

METHODS OF PROVIDING PROPER CON-
DITIONS FOR CHEESE-RIPENING

There are three ways in which the evils resulting
from improper conditions of ripening can be over-
come: (i) Immediate sale and removal of cheese,

(2) providing proper conditions in cheese-factory and

(3) central curing-stations. We will briefly consider
each.

Immediate sale and removal. — In factories which
are provided with no adequate facilities for ripening
cheese, it has in many cases come to be a custom to
sell the cheese before it has had a chance to deteriorate.
So far as the cheese-factory is concerned, this system
relieves it of responsibility for the cheese after its
manufacture; but the factory patrons lose such ad-
vantage as would come from providing good curing-
rooms and holding the cheese. The buyer has an

394 SCIENCE AND PRACTICE OF CHEESE-MAKING

opportunity for any increased profit that comes from
ripening the cheese properly; but too often he has no
equipment for ripening and hastens to dispose of
the cheese as quickly as possible. In such cases the
cheese is put before consumers when it is still so
green as to do injustice to the reputation of the cheese-
maker and the cheese-factory. The most extensive
cheese buyers usually have cold-storage plants and
hold the cheese.

Providing proper conditions in cheese-factory. —
In many cases, probably in the majority of factories,
the best interests of the factory will be conserved by
providing a curing-room as a part of the factory
equipment, such as is described on page 103. This is
practicable, efficient and economical from every point
of view.

Central curing-stations. — In Wisconsin and Canada
the problem of cheese-curing has been solved, to some
extent, by providing buildings, centrally located with
reference to a number of cheese-factories, where the
cheese are taken as soon as practicable and stored
until sold. Such curing-stations are provided with a
modern cold-storage equipment and are able perfectly
to control conditions of temperature and humidity.
The cost of ripening cheese in this way is more than
repaid by the increase of price received for the cured
cheese.

Part IV

Methods of Making Different
Varieties of Cheese :

Stilton.

English Sage.

Cottage.

Pasteurized Neufchatel

Cream.

Club.

Edam.

Gouda,

CHAPTER XXVII

Methods of Making Different Varieties

of Cheese

While the original purpose of the authors was
to confine the matter of the book to the subject of
cheddar cheese, it has seemed desirable to devote
one chapter to a brief description of the methods
of making some other varieties of cheese. We have
chosen for the most part those varieties which can
be made with simple eauipment. Such varieties as
Swiss cheese, for example, can not be properly
treated in a limited way.

STILTON CHEESE

In England Stilton cheese is the most popular of
all blue-mold varieties. In Canada, only a small
quantity of Stilton cheese is manufactured and, in the
United States, a still smaller quantity.

First stages of cheese-making process. — The
method of making modern Stilton cheese does not
vary greatly in the early stages from that of
cheddar cheese-making. Up to the time of salting,
the process is practically the same in both cases. The
main characteristic in Stilton cheese is that it should
contain a uniform growth of blue mold distributed
through its interior mass.

Starting mold-formation. — The salt before being
applied should be mixed with a small amount of

397

C/i

fc:'

1 • ,

HkjA

nBr '

■IB

[ 1 ■ ^

-n

fc.

•s«~^

fcl

MAKING DIFFERENT KINDS OF CHEESE 399

mold growth. As a result of this even distribu-
tion of salt through the curd, the mold becomes
uniformly distributed over the surface of each piece
of curd.

Pressing cheese. — The cheese is made in ordinary
Young-America hoops and should weigh about 12
pounds each. The pressure should be light but con-
tinuous for at least 48 hours.

Ripening process. — To have Stilton cheese ripen
into the best condition it should be kept in a damp,
moldy cellar, where the temperature does not go
above 65° F. Here the cheese soon becomes coated
with blue mold, which influences the ripening
process.

Stilton cheese should not be consumed before it is
at least 2 months old.

ENGLISH SAGE CHEESE

Early stages of process. — Up to the time of mill-
ing, the process is similar to that of cheddar cheese.
The method usually followed is to divide the milk,
placing about one-fourth in a small vat, to which is
added green vegetable coloring-matter at the rate of
12 ounces for 1,000 pounds of milk. The balance of
che milk is handled without being colored. When the
whey is removed, the colored curd is evenly mixed
with the uncolored to produce the desired mottled ap-
pearance. (This result can also be accomplished with-
out dividing the milk by treating the curd with the
coloring-matter just before salting.) Before pressing,
sage flavoring-extract is sprayed over the curd. When

400 SCIENCE AND PRACTICE OF CHEESE-MAKING

finished, the cheese should present a uniformly green
mottled appearance.

Pressing cheese.^ — The regular-sized English sage
cheese weighs about 5 pounds, but in America all sizes
are found, weighing from 2 to 80 pounds. The pres-
sure in hoops should be continuous for 24 to 48 hours.

Ripening process.- — Sage cheese can be ripened in
an ordinary cellar or cool room where the temperature
does not go above 60° F. It should be held until it
has developed the pronounced flavor that is charac-
teristic of the cheese.

COTTAGE-CHEESE

Cottage-cheese is manufactured and consumed
extensively in the United States. The original
Dutch cottage-cheese is the product made by al-
lowing milk to stand until it coagulates by the
ordinary process of souring. The curd is put into
cotton bags to drain, and, after all free whey has
escaped, the curd is salted. It is then pressed into
the form of balls and is ready for immediate con-
sumption.

The modern method of cottage-cheese-making
differs somewhat from the above and gives a more
uniform quality of cheese.

Material to use. — Skim-milk should be used,
as whole-milk loses too much of its fat in the manu-
facturing process.

Preparation and use of starter. — In making cot-
tage-cheese on a large scale, time can be saved and
quality improved by hastening the souring of the
milk through the use of a starter prepared in the

MAKING DIFFERENT KINDS OF CHEESE 4OI

manner already described (p. i8). The character of
the starter Is of much importance, since the flavor of
the cheese almost entirely depends upon it. Impure
starters may cause slimy fermentation, and from such
curd the whey will not separate easily.

1. Method of making cottage-cheese without
starter. — Milk is kept at a temperature of 70° to
75° F. until well curdled, which will usually require
about 48 hours. The curdled mass is then broken
by hand or cut by a curd-knife into large pieces,
which should be as uniform as possible. The tem-
perature is raised to 90° F., where it is kept till
the whey appears clear. Heating should not be
done too rapidly, as it injures the texture of the
cheese. From 30 to 40 minutes should be required
for this. About 15 minutes after completion of
the heating, or when the whey has become well
separated from the curd, the whey is removed and
the curd placed in muslin bags or on racks, where
it is allowed to drain.

The curd is then salted at the rate of i pound for
TOO pounds of curd, or according to taste, then shaped
into pound or half-pound balls, and finally wrapped in
oiled paper. For the finest quality of cheese, the curd,
before being made into balls, should be mixed with
thick, ripened cream at the rate of i ounce of cream
for I pound of cheese.

2. Method of making cottage-cheese with use of
starter. — As soon as the skim-milk is placed in the
manufacturing vat, from 2 to 3 per cent of good
commercial starter is added and thoroughly mixed
through the entire mass. The subsequent steps are
similar to those given in preceding paragraph.

402 SCIENCE AND PRACTICE OF CHEESE-MAKiNG

3. Method of making cottage-cheese with use of
starter and rennet. — The starter is added as pre-
viously described. About 8 hours later rennet-
extract is added at the rate of i ounce for each
1,000 pounds of milk. The rennet should be well
diluted with cold water to prevent too rapid coagu-
lation. The balance of the process is similar to that
already described. When rennet is used, the coagula-
tion can be secured with a smaller percentage of acid
development. About 0.4 per cent acid in the whey
at the time of its removal makes the best flavor and
texture.

4. Method of making cottage-cheese from skim-
milk and buttermilk. — This process is now becoming
popular with manufacturers of cottage-cheese,
since it affords a way of utilizing milk that might
otherwise be wasted. The buttermilk and skim-
milk are mixed in various proportions. The tem-
perature for heating the milk depends on the amount
of buttermilk and the amount of acidity. The
lower the temperature vised consistent with a good
coagulation, the smoother will be the texture of
the cheese. In making cottage-cheese by any of these
methods the quality can generally be improved and
greater uniformity secured by the use of a small
amount of rennet.

5. Method of making cottage-cheese by direct
addition of hydrochloric acid. — Have the milk at
70° to 80° F. Measure out pure hydrochloric acid,
of specific gravity 1.20, at the rate of 10 ounces for
100 pounds of milk. Dilute with ten times its
weight of cold water and add to milk gradually,
stirring the milk constantly while the acid is being

MAKING DIFFERENT KINDS OF CHEESE 403

added. Continue the stirring until the curd sepa-
rates completely, leaving a clear whey entirely
free from milkiness. The whey is then removed from
the curd and the operation completed as before. In
order to get the proper flavor, it will be necessary to
mix with the curd some sour, thick milk or cream.
This method does not give as satisfactory results as
the others described.

Qualities of cottage-cheese. — Flavor and texture
are the most important qualities in cottage-cheese.
The flavor should be that of mildly-soured milk
or well-ripened cream. There should be an entire
absence of all objectionable flavor, such as bitter
taste, stable flavor, etc. If the cheese tastes too sour
it is usually due to keeping too much whey in the
curd. The use of a starter is apt to insure the right
kind of flavor. The texture of cottage-cheese is
largely dependent on the amount of moisture in the
cheese. When the percentage of moisture is much
below 70, the cheese is harsh, dry and sawdust-like.
The right texture of cottage-cheese is smooth and
free from grittiness. Difliculty is often experienced
in securing a uniform quality at all seasons of the
year. The trouble is generally caused by too sud-
den changes in the temperature of the curd or in
the development of lactic acid. Cottage-cheese
should be kept in a cool place. It usually sells for
5 to 10 cents per pound.

Yield of cottage-cheese. — From lOO pounds of
milk one should obtain from 20 to 22 pounds of cheese.
Variation in moisture makes much variation in
yield.

404 SCIENCE AND PRACTICE OF CHEESE-MAKING

Composition of cottage-cheese. — Cottage-cheese
of the best texture contains 70 to 75 per cent of
moisture. Curdhng milk at too high a temperature
and heating the curd too high or too long will make
the cheese too dry. Cottage-cheese contains about
3.5 to 4 per cent of milk sugar and 2 to 2.5 per cent
of nitrogen.

PASTEURIZED NEUFCHATEL CHEESE

This type of soft cheese is one of the most pal-
atable of the kind. It is mild -in flavor and easily
digested.

Method of making. — Place 30 pounds of clean,
sweet, whole-milk in an ordinary, plain shotgun
can. The milk should then be heated to 165° F.
for 20 minutes by placing the can in hot water.
After reaching this temperature it should be imme-
diately cooled to y2° F. When cool, i.o cubic cen-
timeter of clean, commercial starter is added,
diluted in 100 cc. of cold water. When the starter
has been evenly stirred through the milk, rennet
is added at the rate of 0.4 cc. to 30 pounds of
milk. The rennet should be diluted with cold
water, at the rate of i cc. of rennet to 99 cc. of
water. Enough rennet should be used to give a
firm coagulation in 12 hours. As soon as the milk
has become firmly coagulated, it should be poured
from the can onto a strainer-rack where the whey
is allowed to drain from it. At this time, the whey
dripping from the curd should have from 0.30 to
0.32 per cent acidity. High acidity spoils the char-
acteristic flavor and taste. While the curd is dry-
ing, it should have the portions on the outside of

MAKING DIFFERENT KINDS OF CHEESE 405

the strainer stirred into the more moist portion in
the center. This is to prevent hard particles form-
ing from excessive drying. Some pressure may be
used to aid in expelHng the whey. The draining of
whey should be so regulated that, at the time of salt-
ing, it will not have more than 0.40 per cent of acidity.
When all free whey has escaped, salt is applied at the
rate oi i}4 pounds to 100 pounds of cheese. The
cheese is shaped by small cylindrical molds and then
wrapped in parchment paper and tin-foil. After being
kept for 24 hours in a cool place, the cheese is then
ready for eating.

CREAM CHEESE

The manufacture of cream cheese is very similar
to that of pasteurized Neufchatel cheese, with the
exception that the milk is not usually pasteurized.
Milk is modified so that it tests about 10 per cent of
milk-fat. At the time of adding rennet, the acidity
should not be more than 0.15 per cent.

The cheese is shaped by square molds and each
weighs usually about j4 pound.

Sometimes cream cheese is made by adding cream
to the curd of pasteurized Neufchatel cheese just
before salt is applied. This method makes a cheese
of very fine quality.

CLUB-CHEESE

Club-cheese is one of the most extensively used
varieties of cheese. Practically every hotel and
restaurant in every country uses more or less of it.

406 SCIENCE AND PRACTICE OF CHEESE-MAKING

The manufacturing process is simple enough, and yet
the desired quahty is hard to obtain. The value of
the cheese depends entirely upon the quality of the
constituents used.

Method of making. — One grinds 8 pounds of
well-ripened cheddar cheese of finest quality in an
ordinary meat-grinding machine. After the cheese
has been through the machine once, one pound of
butter of the best quality is mixed with it and the
whole mass again run through the machine. The
mixture is then stirred and worked with the hands
till free from all lumps. It is then packed in jars
of some form and must be kept in a cool place. It
is well to smear the inside walls of the jar with
melted butter before packing the cheese in it and
then put a thin layer of melted butter over the top
of the packed cheese before putting on cover.
Finest club-cheese usually sells for about 40 cents a
pound.

EDAM CHEESE

Edam cheese is a sweet-curd cheese, made from
partially skimmed milk. It comes to the market in
the form of round, red balls, each weighing from 3}^
to 4 pounds when cured. They are largely manu-
factured in Northern Holland and derive their name
from a town which is famous as a market for this
kind of cheese

Kind of milk used. — Milk from which one-fourth
to one-third of the fat has been removed is used.
Too great pains cannot be taken in regard to the
condition of the milk. It should be fresh, free from

MAKING DIFFERENT KINDS OF CHEESE 407

every trace of taint; in brief, it should be in as per-
fect condition as it is possible to have milk.

Treatment of milk before adding rennet. — The
temperature of the milk should be brought up to a
point not below 85° F. nor much above 88° F. When
the desired temperature has become constant, then the
coloring-matter should be added to the milk and
thoroughly incorporated by stirring before the rennet
is added.

Addition of rennet to milk. — When the tempera-
ture reaches the desired point 85° to 88° F. and
remains there stationary, the rennet-extract is
added, 4^ to 5^ ounces being taken for 1,000
pounds of milk, or enough to coagulate the milk
in the desired time, at the actual temperature used.
The milk should be completely coagulated, ready
for cutting, in about 12 to 18 minutes from the time
the rennet is added. The same precautions observed
in making cheddar cheese should be followed in
making Edam cheese with reference to care in add-
ing the rennet, such as careful, accurate measurement,
dilution with pure water before addition to milk,
etc.

Cutting the curd. — When the curd breaks clean
across the finger, it should be cut; the curd is cut a
very little softer than in the cheddar process as
ordinarily practiced. First, a vertical knife is used
and the curd is cut lengthwise, after which it is
allowed to stand until the slices of curd begin to
show the separation of whey. Then the vertical
knife is used in cutting crosswise, after which the
horizontal knife is at once used. Any curd adher-
ing to the bottom and sides of the vat is carefully
removed by the hand, after which the curd-knife is

408 SCIENCE AND PRACTICE OF CHEESE-MAKING

again passed through the mass of curd lengthwise and
crosswise, continuing the cutting until the curd has
been cut as uniformly as possible into very small
pieces.

Treatment of curd after cutting. — When the cut-
ting is completed, then one commences at once to
heat the curd up to the temperature of 93° to 96°
F. The heating is done as quickly as possible.
While the heating is in progress, the curd is kept
constantly agitated to prevent settling and conse-
quent overheating. As soon as the curd shows
signs of hardening, which the experience of the
worker will enable him to determine, the whey is
drawn off until the upper surface of the curd ap-
pears, when one should commence to fill the press-
molds.

Filling molds, pressing and dressing cheese. —
The molds, which are described later in detail, are
well soaked in warm water previous to use, in
order to prevent too sudden chilling of curd and
consequent checking of separation of whey. As
soon as the whey is drawn off, as indicated above,
one commences to fill the pressing-molds. The fill-
ing should be done as rapidly as possible to prevent
too great cooling of curd. When the curd has been
put into the molds, its temperature should not be
below 88° F. Unless care is taken to keep the
curd covered, the portion that is last put into the
molds may become too much cooled. In making
Edam cheese on a small scale, it is a good plan to
squeeze the moisture out by the hands as much as
possible and then break it up again before putting
in the molds, when the curd should be pressed

MAKING DIFFERENT KINDS OF CHEESE 409

into the mold by the hands as firmly as possible.
The molds should be filled as nearly alike as pos-
sible. The cheese should weigh from 5 to 5^4
pounds each when ready for the press. When the
filling of molds is completed, they are put under
continual pressure of 20 to 25 pounds for about 25
or 30 minutes. While the cheese is being pressed,
some sweet whey is heated to a temperature of 125°
or 130° F. and this whey should not be allowed to
go below 120° F. at any time while it is being used.
When the cheeses are taken from their molds, each
is put into the warm whey for two minutes, then
removed and dressed. For dressing Edam cheese
the ordinary cheese-bandage cloth is used. This is
cut into strips which should be long enough to
reach entirely around the cheese and overlap an
inch or so, and which should be wide enough to
cover all but a small portion of the ends of the
cheese when put in place. Before putting on the
bandage, all rough projections should be carefully
pared from the cheese. In putting on the bandage,
the cheese is held in one hand and the bandage is
wrapped carefully around the cheese, so that the
whole cheese is covered, except a small portion
on the upper and lower surface of the cheese.
These bare spots are covered by small pieces of
bandage cloth of a size sufficient to cover the bare
surface. The bandage is kept wet with the warm,
sweet whey, thus facilitating the process of dress-
ing. After each cheese is dressed, it should be
replaced in the pressing-mold, care being taken
that the bandage remains in place and leaves no
portion of the surface of the cheese uncovered and

410 SCIENCE AND PRACTICE OF CHEESE-MAKING

in direct contact with the mold. The cheese is then
put under continual pressure of 60 to 120 pounds
and kept under this continual pressure for 6 to 12
hours.

Salting and curing. — There are two methods
which may be employed in salting, dry-salting and
wet-salting. In dry-salting, when the cheese is finally
♦ taken from the press, it is removed from the press-
mold, its bandage is removed completely and the
cheese placed in another mold, quite similar, known
as the salting-mold. Each cheese is placed in a
salting-mold with a coating of fine salt completely
surrounding it. The cheese is salted in this way
once each day for 5 or 6 days. Each day the cheese
should be turned when it is replaced in the mold,
so that it will not be rounded on one end more
than another. This is for the purpose of making
both ends uniform in shape, giving each the proper
rounding peculiar to the shape of the cheese. In
the method of wet-salting, the cheese is placed
in a tank of salt brine, made by dissolving common
salt in water in the proportion of about one pound
of salt to 2}^ quarts of water. Each cheese is
turned once a day and should be left in the brine 7
or 8 days. When the cheese is taken from the
salting-mold or salt bath it is placed in warm water
and is given a vigorous, thorough brushing in order
to remove all slimy or greasy substances that may
have accumulated on the outer surface of the
cheese. When the surface of the cheese is well
cleansed, it is carefully wiped dry with a linen
towel and placed upon a shelf in the curing-room.
In being placed on the shelves, the cheeses should

MAKING DIFFERENT KINDS OF CHEESE 4II

be placed in contact so as to support one another,
until they have flattened out at both ends so much
that they can stand upright alone. Then they are
placed far enough apart to allow a little air space
between them. Another method of securing the
flattened ends is to support each cheese on opposite
sides by wedge-shaped pieces of wood. After they
are placed on the shelves in the curing-room, they
are turned once a day and rubbed with the bare
hand during the first month, twice a week during
the second month, and once a week after that.
When any slimy substance appears on the surface
of the cheese, it should be washed off at once with
warm water or sweet whey. The special conditions
of the curing-room will be noticed in detail below.
When the cheeses are about two months old, they
can be prepared for market, which is done in the
following manner: They are first made smooth on
the surface by being turned in a lathe or in some
other manner, after which the surface is colored.
For coloring, some carmine is dissolved in alcohol
or ammonia to get the proper shade, and in this
color-bath the cheeses are placed for about one min-
ute, when they are removed and allowed to drain,
and as soon as they are dry the outside of each
cheese is rubbed with boiled linseed oil, in order to
prevent checking. They are then wrapped in tin-
foil, which is done very much like the bandaging.
Care must be taken to put the tin-foil on so that it
presents a smooth, neat appearance. The cheeses
are finally packed in boxes, each box containing 12
cheeses, arranged in two layers of six each, with a
separate partition for each cheese. .

412 SCIENCE AND PRACTICE OF CHEESE-MAKING

Curing-room. — Much more attention must be
given to the condjitions of the curing-room as re-
gards moisture and temperature than in the case of
cheddar cheese. The curing-room should be well
ventilated, should be quite moist and its tempera-
ture should be kept between 50° and 65° F. These
conditions are best secured in some form of
cellar.

Utensils employed in making Edam cheese. —

Aside from the molds, continual press and salt-
ing-vat, the same apparatus that is used in making

FIG. 50 — EDAM PRESS-MOLD AND COVER

cheddar cheese can be used in making Edam cheese.
The pressing-mold is turned preferably from white
wood or, in any case, from wood that will not taint.
Each mold consists of two parts ; the lower part
constitutes the main part of the mold, the upper
portion is simply a cover. The lower portion or
body of the mold has several holes in the bottom,
from which the whey flows when the cheese is
pressed. Care must be taken to prevent these holes
being stopped up by curd. This portion of the
mold is about 6 inches deep and 6 inches in diam-
eter across the top. The salting-mold has no cover

MAKING DIFFERENT KINDS OF CHEESE

413

and the bottom is provided with only one hole for
the outflow of whey ; in other respects it is much
like the pressing-mold.

Fig. 50 shows the external appearance of the
press-mold with cover in position, the inner surface
of the cover, and the inside appearance of the press-
mold. Fig. 51 shows the press-mold and cover in

FIG. 51 — CROSS-SEC-
TION OF EDAM
PRESS-MOLD AND
COVER

FIG. 52 — EDAM SALT-
ING-MOLD IN CROSS-
SECTION

cross-section. Fig. 53 shows the salting-mold in
external and internal appearance and Fig. 52 shows
cross-section of the same.

Qualities of Edam cheese. — The flavor of a per-
fect Edam cheese is difficult to describe. It is mild,
clean and pleasantly saline. In imperfect Edams the
flavor is more or less sour and offensive.

In body, a perfect Edam cheese is solid, rather dry
and mealy or crumbly. This condition is secured
by the use of partially skimmed milk, together with
the special conditions of manufacture employed.

414 SCIENCE AND PRACTICE OF CHEESE-MAKING

In texture, the perfect Edam cheese should be close
and free from pores.

Some general remarks. — There are a few points
which may be best brought to our attention by con-
trasting some of the conditions used in the manufac-
ture of Edam cheese with those employed in the
manufacture of our American cheddar cheese.

(i) One is made from partially skimmed milk;
the other, when at its best, is made from whole
milk.

FIG. 53 — SALTING-MOLD, INSIDE AND
OUTSIDE APPEARANCE

(2) While it is very important in making cheddar
cheese to have the milk in perfect condition, it is abso-
lutely essential in making Edam cheese.

(3) In making cheddar cheese, the removal of
moisture is largely effected in the vat by the use of
a higher temperature in heating the curd. In mak-
ing Edam cheese, the removal of moisture depends
more upon the fineness of cutting the curd and sub-
sequent pressing. The latter process is much less
economical as regards loss of milk constituents.

(4) In making cheddar cheese, more or less
lactic acid is formed according to special condi-
tions; in making Edam cheese, every effort is made

MAKING DIFFERENT KINDS OF CHEESE 415

to hasten the process at every stage and prevent the
formation of lactic acid. In one case, we work to
produce an acid curd; in the other, a curd as free as
possible from acid.

(5) The details of salting and curing differ
radically in the two methods. In general, the
manufacture of Edam cheese requires labor and care
in giving attention to many more details than the
manufacture of cheddar cheese, however much the
latter should have for best success.

(6) Edam cheese sells for two or three times as
much per pound as the best American cheddar.

GOUDA CHEESE

Gouda cheese is a sweet-curd cheese made from
whole-milk. In shape, the Gouda cheese is somewhat
like a cheddar with the sharp edges rounded off and
sloping toward the outer circumference at the middle
from the end faces. They usually weigh lo or 12
pounds each, though they vary in weight from 8 to
16 pounds. They are largely manufactured in southern
Holland, and derive their name from the town of the
same name.

Kind of milk used. — Fresh, sweet milk that has
been produced and cared for in the best possible
manner.

Temperature of milk before adding rennet. — The

temperature of the milk should be brought up to a
point not below 88° F. nor much above 90° F. When
the desired temperature has been reached and has
become constant, then the coloring-matter is added
and thoroughly incorporated by stirring before the
rennet is added.

4l6 SCIENCE AND PRACTICE OF CHEESE-MAKING

Addition of rennet to milk. — The rennet should
not be added until the milk has reached the desired
temperature (88° to 90° F.) and this temperature has
become constant. Then one adds 4 to 5 ounces of
fresh rennet-extract for 1,000 pounds of milk. The
milk should be completely coagulated, ready for
cutting, in 15 or 20 minutes. The same precautions
should be used in adding rennet as those previously
mentioned in connection with the manufacture of
Edam cheese.

Cutting the curd. — The curd should be cut when
it is of about the hardness generally observed for
cutting in the cheddar process. The cutting is done
exactly as in the cheddar process except that the
curd is cut a little finer in the Gouda cheese. Curd
should be about the size of peas or wheat kernels
when ready for press and as uniform in size as
possible.

Treatment of curd after cutting. — When the cut-
ting is completed, one commences at once to heat
the curd and to stir carefully. The heating and
constant stirring are continued until the curd
reaches a temperature of 104° F., which should
require from 30 to 40 minutes. When the curd be-
comes rubber-like in feeling and makes a squeak-
ing sound when chewed, the whey should be run
ofif. The whey should be entirely sweet when it is
removed.

Pressing and dressing cheese. — After the whey
is run off, the curd is put in the molds at once
without salting. Pains should be taken in this proc-
ess to keep the temperature of the curd as near
100° F. as possible. Each cheese is placed under

MAKING DIFFERENT KINDS OF CHEESE 417

continual pressure amounting to lo or 20 times its
own weight and kept for about half an hour. The
first bandage is put on in very much the same man-
ner as the bandage in Edam cheese-making. The
cheese is then put in press again for about one hour.
The first bandage is then taken off and a second one
like the first one put on with great care, taking pains
to make the bandage smooth, capping the ends as
before. The cheese is then put in press again and
left 12 hours or more.

Salting and curing. — When the cheese is taken
from the press the bandage is removed and it is
placed for 24 hours in a curing-room like that used
in curing Edam cheese, as previously described (p.
412). Each cheese is then rubbed all over with dry
salt until the salt begins to dissolve, and this same
treatment is continued twice a day for ten days.
At the end of that time, each cheese is carefully
and thoroughly washed in warm water and dried
with a clean linen towel. The cheeses are then
placed on the shelves of the curing-room, turned
once a day and rubbed like cheddars. The tempera-
ture and moisture are controlled as described in the
curing process of Edam cheese. If the outer surface
of the cheese gets slimy at any time, they are care-
fully washed in warm water and dried with clean
towels. Under these conditions, the cheese ripens in
2 or 3 months.

Utensils employed in making Gouda cheese. —

The molds, continual press and curing-room are
the only things needed in the making of Gouda
cheese that differ from the utensils employed in
making cheddar cheese. The mold used for Gouda

4i8 SCIENCE And practice of Cheese-making

cheese consists of two parts, which are shown
separate in Fig. 54, while in Fig. 55 the two parts
are shown united, ready for pressing. These molds
were made of heavy pressed tin. The inside diam-
eter at the middle is about 10 inches. The diameter
of the ends is about 6^ inches. The height of the
mold (as seen in Fig. 55) is about 5^ inches, and
this represents the thickness of the cheese, but by
pushing the upper down into the lower portion, the

a b

fig. 54 — two parts of

gouda mold, shown

separate

FIG. 55 TWO PARTS OF

GOUDA MOLD, UNITED

thickness can be decreased as desired. A simple
way to make a Gouda mold is to take two rounded
wash basins made of pressed tin, cut them down
so that they will be about i^ inches deep. Then
on one portion is soldered a rim of tin about 3
inches wide (see Fig. 54 A, or Fig. 55, lower por-
tion of mold). On the second wash basin is sol-
dered another rim of tin 3 inches wide, about Yi
inch of which projects beyond the open side of
the wash basin, the rest projecting on the other
side (see Fig. 54 B and Fig. 55, upper portion).
This upper part, or B, should be made of such
diameter that it will just fit into the inside of the

MAKING DIFFERENT KINDS OF CHEESE 4I9

other portion, as shown in Fig. 55. The upper por-
tion is provided with two rings soldered on and the
lower portion with two handles to facilitate handling.
In the ends of the molds or the portions made from
wash basins there are 18 or 20 perforations about %
inch in diameter, made for the purpose of letting the
whey run out.

Part V

Methods of Testin
Cheese-Factory Organization
Literature of Cheese-Makin

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PUBLOW'S APPAR-ATTiq RTV? ,«*r:A cTiB)*\Ty-< ^ r^u-^is-a

CHAPTER XXVIII

Methods of Testing Used in Cheese-Making

It is our purpose in this chapter to give, for the
most part, only an outHne of the methods of testing*
used in connection with cheese-making, since the full
details would occupy too much space. The methods
to be considered cover the following substances :

1. Fat in (i) milk, (2) whey, (3) curd, and (4)
cheese.

2. Acidity in (i) milk, (2) whey, (3) curd, and
(4) cheese.

3. Strength of rennet-extracts.

4. Dirt and ferments in milk.

5. Specific gravity.

6. Hot-iron test.

7. Casein in milk.

THE BABCOCK TEST FOR FAT

This is a method for determining the amount of
fat in milk and its products. The test is based (i) on
the action of strong sulphuric acid upon the solids
of milk other than fat, by which the milk-fat is
released from the restraining influence of other com-
pounds and so is free to collect in one separate mass,
and (2) on the use of centrifugal force, which is em-
ployed to complete separation of the fat. The Bab-

*For a full description of all the details of most of these methods, see
"Modem Methods of Testing Milk and Milk Products," published by the
Orange Judd Company.

423

424 SCIENCE AND PRACTICE OF CHEESE-MAKING

cock test finds occasion for use in connection with
cheese-making in the following ways : ( i ) Testing
milk of individual patrons when dividends are made
on the basis of the milk-fat; (2) testing milk to
ascertain if its fat content has been seriously affected
by skimming; (3) testing milk to use as a basis for
estimating the yield of cheese and regulating the
amount of salt used (p. 38) ; (4) testing whey
and press-drippings to ascertain if the loss of fat
is excessive, and (5) testing cheese for percentage
of fat.

Apparatus and materials used. — The following list
includes the apparatus and materials used in making
this test: (i) Test-bottles, graduated from o to 10
per cent, so that each smallest division represents 0.20
per cent when 17.5 cubic centimeters (18 grams) of
milk are used; (2) pipette for measuring milk, hold-
ing 17.6 cubic centimeters to mark; (3) measure
for acid, holding 17.5 cubic centimeters to mark;
(4) centrifugal machine, having a wheel 12 to 20
inches in diameter, easily capable of being run at a
speed of 700 to 1,200 revolutions a minute; and (5)
commercial sulphuric acid having a specific gravity
between 1.82 and 1.83, preferably just 1.825 (Test-
ing Milk, etc., pp. 32-52).

Sampling milk for testing. — Milk that has curdled,
or on the surface of which cream has risen and dried,
or milk the fat of which has partially churned, is- dif-
ficult to sample. These difficulties should not be com-
mon in cheese-factory work, but, when they arise,
careful attention should be given to the details pre-
scribed for such cases (Testing Milk, etc., pp. 22-
24). The samples to be tested must be thoroughly
mixed.

TESTS USED IN CHEESE-MAKING 425

Composite samples. — In order to avoid testing
milk daily, composite samples may be prepared and
tested at intervals of a week or ten days. Much care
must be used in preparing and keeping composite
samples (Testing Milk, etc., pp. 24-31).

Method of operating the test. — (Testing Milk
etc., pp. 53-66). In brief outline, the different
steps are given as follows :

(i) Mix thoroughly sample of milk, which is at
60° to 70° F.

(2) Quickly fill pipette to mark with milk.

(3) Run milk into test-bottle.

(4) Fill acid-measure to mark with acid and pour
into test-bottle.

(5) (a) Mix milk and acid thoroughly by rotary
motion; (b) let stand 2 to 5 minutes; and (c) mix
again.

(6) Put test-bottles in tester (centrifuge) and
whirl 4 or 5 minutes at proper speed.

(7) (a) Add fairly hot water up to neck of bot-
tles; (b) whirl one minute; (c) add hot water to
8 or 9 per cent mark; and (d) whirl one minute.

(8) Read results at temperature of about 130° F.

Special precautions. — The following statements
give an outline of the particular points to be observed
in making the test in order to insure accuracy:

(i) Always make tests in duplicate.

(2) Make sure that the saniple is a representative
one.

(3) Have the temperature of the milk and acid at
60° to 70° F. before putting in test-bottle.

(4) Use only acid of right strength.

426 SCIENCE AND PRACTICE OF CHEESE-MAKING

(5) Mix milk and acid thoroughly as soon as aeid
is added.

(6) Mix a second time after a short interval.

(7) Make sure that the tester runs at the right
speed and does not jar.

(8) Use only clean, soft water in filling bottles.

(9) Read bottles before they cool and at about
130° F.

(10) To guard against mistakes, read each test
twice.

Testing whey for fat. — The test' is conducted in
the usual way, except that special bottles having small
necks for more accurate reading are used and less acid
is generally sufficient (Testing Milk, etc., pp. 81-

83).

Testing curd and cheese. — Care must be taken in
sampHng. The weighed sample (8 to 10 grams) is
treated in the test-bottle with about 10 cc. of water
(65°-70° F.), after which the acid (17.6 cc.) is added
and the test completed in the usual way (Testing Milk,
etc., pp. 83-85). The acid should be added carefully,
about I cc. at a time, mixing the acid and water by
shaking after each addition. After all the acid has
been thus added, shake the whole vigorously until the
cheese is completely disintegrated.

TEST FOR ACIDITY

Fresh milk contains substances (casein and acid
phosphates) which neutralize alkali and in this respect
behave like acids. The amount of this acidity is ap-
proximately equivalent to o.io per cent. Amounts of
acid above this figure are usually due to the action of
lactic acid that has been formed by the bacterial decom-

TESTS USED IN CHEESE-MAKING 427

position of the sugar in the milk. It is the amount of
•acid thus formed which we usually desire to determine.

The method of ascertaining the acidity of milk is
based upon the chemical action taking place between
acids and alkalis. Acids and alkalis neutralize each
other and form compounds called salts, which are
neutral (neither acid nor alkaHne). A substance used
in showing whether a solution is acid, alkaline or
neutral is called an indicator. The one in most com-
mon use is a compound called phenolphthalein, which
turns pink in alkali solutions and colorless in acid or
neutral solutions. Only a few drops need be used in
making one test. There are several different methods
for testing acidity, but all are alike in principle.

Publow's acid test. — (i) The apparatus (p. 422)
consists of (i) a plain 5-pint bottle with an opening
in the bottom, through which a brass pipe is connected
so securely as to prevent leakage. (2) A small 2-ounce
wash-bottle, fastened to the neck of the large bottle
by a copper band and connected by means of rubber
corks and glass tubing. (3) A plain 10 cc. burette
graduated in tenths and a simple wire burette-holder.
(4) A straight, non-bulbous, 9-gram pipette, which
can be easily cleaned. (5) A simple rubber-stoppered
dropping-bottle. (6) A plain white cup and stirring-
rod. (7) A small bottle containing 50 cc. of a solu-
tion of caustic soda (equal to 9.2 grams of purest
caustic soda), which, when added to 2,250 cc. of water,
makes 2,300 cc. of a tenth-normal alkali solution. The
large bottle is marked to show the level of 2,300 cc. in
order to save time in measuring. (8) A small bottle
of phenolphthalein indicator.

(2) Preparing alkali solution. — As the most ac-
curate, convenient and economical method of prepar-

428 SCIENCE AND i'RACTICE OF CHEESE-MAKING

ing a tenth-normal alkali solution, a concentrated solu-
tion of caustic soda is advised, of which 50 cc. is suffi-
cient to make 2,300 cc. of a tenth-normal solution. This
solution retains its strength indefinitely when tightly
corked. The tenth-normal solution is prepared by
adding the contents of the small bottle of alkali to the
large bottle without any loss, rinsing the small bottle
several times and each time pouring the rinsings into
the large bottle. Soft water is then added to the large
bottle until it reaches the level of the mark (2,300 cc.)
filed on the bottle. In order to keep this alkali solution
without loss of strength, the small wash-bottle referred
to above (2) is attached to the neck of the larger one
in the manner indicated, after being half filled with the
tenth-normal alkali solution.

(3) Method of use. — The liquid to be tested (milk,
whey, cream or starter) is measured by means of the
9-gram pipette and run into the white cup. Two drops
of phenolphthalein solution are added, after which the
alkali, a drop at a time, is run into the cup from the
burette (arranged in the manner indicated on p. 422),
until the solution in the cup, which must be constantly
stirred, shows a very faint pink color that does not
disappear for 15 seconds or longer. Each tenth cc. of
alkali used represents .01 per cent of acid.

Manns' acid test. — For details see Testing Milk,
etc., pp. 101-103.

Farrington's alkaline tablet test. — In this form of
test, the alkali and indicator are mixed together in the
form of tablets. Five tablets are dissolved so as to
make 97 cubic centimeters of solution, which is added,
in small portions, from a graduated cylinder to 17.5
cubic centimeters of milk until the pink color re-
mains. Each cubic centimeter of alkali solution

TESTS USED IN CHEESE-MAKING 429

used stands for o.oi per cent of acidity equivalent to
lactic test (Testing Milk, etc., pp. 103-105).

Testing acidity of whey. — Whey is tested in the
same manner as milk. The sample of whey tested
should be free from all curd particles, since curd has
some power to neutralize alkali (Testing Milk, etc.,
pp. 109-110).

Testing acidity of cheese. — An extract of a
weighed amount of cheese is made and this extract
is tested for acidity in the usual way (Testing Milk,
etc., p. no).

Special precautions in making acidity tests. —
In carrying out tests for acidity, certain points of the
operation must be kept carefully in mind.

(i) The material tested must be thoroughly mixed
before taking a sample.

(2) The water used in preparing the alkali solu-
tion should be neutral, soft and clean. Distilled water
is best.

(3) Alkaline tablets must be kept dry.

(4) The alkali solution, whichever form is used,
must be kept from contact with air as much as pos-
sible to prevent change of strength.

(5) Prepare fresh solution of alkaline tablets for
best results.

(6) Make tests only in a good light.

QUICK TEST FOR ACIDITY OF MILK

It is often desirable to ascertain quickly whether
milk or cream contains more or less than 0.2 or 0.3
per cent of acid. This can be done by the following
method : An alkali solution is prepared by dissolving
in an 8-ounce bottle 2 alkali tablets for each ounce

430 SCIENCE AND PRACTICE OF CHEESE-MAKING

of water used. A No. lO brass cartridge shell, on
which a wire handle is soldered, is used for meas-
uring the sample to be tested and also the alkali. A
cartridgeful of milk is placed in a teacup and then
a cartridgeful of the alkali solution is added. The
contents of the cup are mixed by a rotary motion.
If the sample tested remains white, it contains over
0.2 per cent of acidity ; if a pink color remains, the
acidity is less than 0.2 per cent. The intensity of the
pink color indicates the relative amount of acid pres-
ent, since the color will be more intense in proportion
as there is less acid. Any other measure may be used
in place of the brass cartridge-shell, but in every case
care must be taken to use equal amounts of milk and
of alkali solution.

This test can be used at the weigh-can in case of
milks that are suspected of containing 0.2 per cent or
more of acid.

THE MARSCHALL TEST

In this test the same general procedure is followed
as in the Monrad test, but the rate of coagulation is
observed in a different way. The following pieces
of apparatus are used: (a) A testing cup or basin,
of about a pint capacity, for holding the milk to
be tested. On the inside wall of this cup there are
graduated spaces beginning with zero at the top and
going by half-divisions to 7 near the bottom of the
cup, while in the bottom of the cup is a glass tube
with a very small bore, (b) An ounce bottle with 3
mark on it to indicate 20 cc. (c) A spatula for stir-
ring the milk, (d) A i cc. pipette.

TESTS USED IN CHEESE-MAKING 43 1

The operation of conducting this test is as follows :
Measure with the pipette i cc. of the rennet-extract
used and empty it into the ounce bottle, previously
half filled with clean, cold water. Rinse the pipette
two or three times by drawing water into it from the
bottle and allowing it to run back into the bottle. Mix
well by shaking. Then place the milk to be tested
in the test-cup, setting it in a level position and allow-
ing the milk to run out at the bottom. Taking the bot-
tle of diluted rennet in one hand and the spatula in
the other, watch the level of the milk in the cup. The
moment the upper surface of the milk drops to the
zero mark, pour the diluted rennet into the rniik and
stir well. Then leave it alone. When the milk coagu-
lates, it stops running through the glass tube. From
the graduated scale, read the number of spaces un-
covered on the inside of the cup, showing how many
divisions of milk have run out. The more slowly the
milk coagulates, the larger the amount that runs out ;
the more quickly the milk coagulates, the smaller the
amount that runs out and the fewer spaces there are
uncovered. When about 2^ spaces are uncovered,
the milk is ready for addition of rennet. The tempera-
ture must be watched, being tested at the start and
finish, especially in a cold room.

Some objectionable features of the Marschall test
should be noticed. A difference in the size of the bore
of the glass tube in the bottom of the cup obviously
makes a difference in the results. It is found that the
size of the bore of the glass tubing varies in different
cups. Therefore, the results given by one cup can not
be compared with those of another, unless they are
tested on the same milk and found to agree. Special

43^ SCIENCE AND PRACTICE OF CHEESE-MAKING

pains must be taken to keep the tube open, since a lit-
tle dirt quickly stops it. The Marschall test is con-
venient for ordinary work, but is not capable of as
great delicacy as is the Monrad test. Results obtained
by different workers can be compared by the Monrad
test, but not by the Marschall test

THE MONRAD TEST

This test is based upon the amount of time required
for a definite quantity of milk at a given temperature
to become coagulated by a fixed quantity of rennet.

The pieces of apparatus required are the following:
(i) A tin cylinder for measuring milk, holding, when
full, 1 60 cc, (2) a 5 cc. pipette, (3) a 50 cc. glass
flask, (4) a thermometer, and (5) a half-pint tin basin.

In testing the ripeness of milk by means of rennet-
extract, one first prepares a dilute solution of the
rennet, as follows : One measures with the small pi-
pette 5 cc. of rennet-extract into the 50 cc. flask. The
pipette is then rinsed twice with water by sucking it
full of cold, clean water to the mark, the rinsings also
being run into the 50 cc. flask. The flask is then filled
with water to the 50 cc. mark, and the contents are
well mixed by shaking. The next step is to fill the
tin cylinder with the well-mixed milk to be tested and
this is emptied into the half-pint basin. The milk
must be at the temperature at which one adds the
rennet in cheese-making, which is generally about
84° to S6° F. To the milk at the desired tempera-
ture, one adds 5 cc. of the diluted rennet solution,
mixes it through the milk quickly, using the ther-
mometer as a stirrer. The exact time when the

TESTS USED IN CHEESE-MAKING 433

rennet-extract is added to the milk is noted by the
second hand of a watch, and then again when the
milk has coagulated; the number of seconds re-
quired to coagulate the milk is recorded. The
exact point of coagulation can be seen more
sharply by scattering a few particles of charcoal
(as the blackened end of a partly burned match)
on the surface of the milk, and then with the ther-
mometer starting the surface into motion around the
dish. The black particles stop the instant the milk
coagulates. By using a stop-watch great accuracy
and delicacy can be attained. Care should be taken
to keep the temperature of the milk at the one desired
point, testing frequently with the thermometer; and
in case the temperature drops, it can be raised by
placing the basin of milk in warm water. In ordinary
cheddar cheese-making, milk is ready for the addition
of rennet when it coagulates in 30 to 60 seconds under
the foregoing conditions.

METHOD OF TESTING RENNET-EXTRACTS

Different brands of rennet-extract vary somewhat
in their strength , that is, the rapidity and completeness
with which they coagulate milk when used in the same
amount. It is therefore important to have a means of
testing their strength, in order that their value may
be definitely known and that cheese-makers may be
able to know in advance of using how much they must
use for the best results. The Monrad and Marschall
tests are available for this purpose.

In order to test the comparative strength of differ-
ent rennet-extracts, one treats different portions of
the same milk with the different extracts to be tested.

434 SCIENCE AND PRACTICE OF CHEESE-MAKING

In all other respects, the details of the methods pre-
viously given are followed. All conditions must be
kept alike in the different tests. The strength of the
renne't-extracts is shown by the rapidity with which
the milk is coagulated; the stronger the rennet, the
less the time of coagulation.

METHOD OF TESTING PEPSIN

Pepsin is beginning to be used in cheese-making as
a substitute for rennet-extract. Vivian has worked
out the important details. The scale-pepsin, of strength
known as 1-3CXDO, prepared from stomachs of sheep,
is recommended. It may be used at the rate of 5
grams for 1,000 pounds of milk. In testing scale-
pepsin by the rennet-test, one can dissolve the scale-
pepsin at the rate of 5 grams in 4 ounces of water
and use this solution exactly like a rennet-extract with
milk. It should be tested in comparison with a sam-
ple of rennet-extract whose use in cheese-making has
been tested, the test being made on different portions
of the same milk.

TESTS FOR FERMENTS AND INSOLUBLE

DIRT IN MILK

Those forms of micro-organisms or ferments that
make trouble in cheese-making are not readily per-
ceptible to the senses when milk is delivered at the
cheese-factory, but the results of their work develop
later either during the cheese-making process or later
in ripening cheese. When such ferments appear,
it is desirable to locate them in some particular herd
or herds with a view to removal of the causes of

TESTS USED IN CHEESE-MAKING 435

trouble. It is also desirable to get an idea of the
amount of suspended dirt in milk, as this may often
be an indication of the general bacterial condition of
the milk, since bacteria generally keep company with
dirt. We have tests for accomplishing these objects.

TEST FOR DIRT IN MILK

The following is a quick, simple, practicable method
for indicating in a rough way how much suspended
dirt milk contains : Provide several granite-iron fun-
nels 2^ or 3 inches in diameter. Place in these some
clean absorbent cotton, making the upper surface as
smooth and flat as practicable and somewhat compact.
Have these near the weighing-can so that one can be
attached on inside of can. When milk is dumped in
can and thoroughly mixed, take a pint and pour on
cotton in funnel. Any suspended dirt quickly shows.
The method might be improved by laying a circular
piece of white muslin on top of the cotton. The test
performed under the eyes of a patron would be con-
vincing. Milk should contain no visible dirt in sus-
pension.

THE FERMENTATION OR WISCONSIN

CURD-TEST

Milk frequently contains objectionable forms of
organisms or ferments that are not made perceptible
by ordinary methods of observation. The condition
arises particularly in milk used for cheese-making and
may result in serious injury to the quality of the
cheese. The Wisconsin experiment station (Wisconsin
experiment station 12th and 15th annual reports,
1895 and 1898) has applied certain principles to the

43<J SCIENCE AND PRACTICE OF CHEESE-MAKING

development of a test that enables one to identify milk
containing certain forms of undesirable ferments likely
to do serious injury. This method is based, in gen-
eral, upon the plan of making conditions favorable for
the rapid development of the ferments present in milk.
Apparatus. — The apparatus consists of the follow-
ing parts : (i) Pint glass jars or tin cans with covers,
(2) a well-insulated tank to hold the jars, (3) rennet-
extract, (4) a thermometer, (5) a case-knife or sim-
ilar instrument for cutting curd, .and (6) a small
pipette for measuring rennet-extract.

Operation of test. — The test is conducted as fol-
lows: The jars, including covers, just previous to
use, are sterilized with live steam, scalding water or
dry heat (212° F.). Each jar or can is filled about
two-thirds full with the milk to be tested and the ster-
ilized cover put on at once. The jars are then placed
in the tank which is filled with water at 100° to 102°
F. up to the upper surface of the milk in the jars. The
temperature of the water should be kept at 100° to
102° F. during the whole operation. To hasten the
warming of the milk, the jars are taken out and shaken
occasionally. The temperature of the milk is observed
with a sterile thermometer, and when the milk has
reached 98° F., one adds 10 drops of rennet-extract
to each jar and mixes thoroughly by giving the con-
tents of the jar a rotary motion. When the milk has
coagulated, it is allowed to stand until it is firm, usu-
ally about 20 minutes. To enable the whey to sepa-
rate more readily, the curd is then cut fine with a
thin knife, which must be carefully rinsed with hot
water after finishing each jar and before using it in
another, in order to avoid carrying contamination from

TESTS USED IN CHEESE-MAKING 437

one milk to another and spoiling the test. The curd
is allowed to settle completely. When the whey has
been separating half an hour, the samples are exam-
ined for flavor by smelling, after which the whey
is carefully poured out of the jars and this is repeated
at intervals of 30 to 40 minutes for 8 hours or more.
Under the favorable conditions of temperature, similar
to those employed in cheese-making, the organisms
present develop readily and reveal their presence in
different characteristic ways. The jars are finally
opened, any whey present is drained off, and the fol-
lowing tests are applied : ( i ) The curd is cut into two
pieces. The curd will be solid and free from holes
on the cut surfaces, if the milk is not tainted. If it
is spongy and full of holes, it contains those undesir-
able organisms that produce gases in the curd and in-
jure it for cheese-making, showing in the form of
''floating curds" and ''huffy" cheese. The holes are
usually small, their common name being "pin-holes."
(2) The curd is examined with reference to any
marked disagreeable odors that may be present. Some
undesirable organisms reveal their presence by smell
without making spongy curd. This may, perhaps, be
best perceived by smelling of a freshly cut surface
of the curd. Offensive odors are, of course^ an unde-
sirable indication. Special apparatus for perform-
ing the test is furnished by dairy-supply houses, but
pint fruit- jars and other home-made appliances will
answer satisfactorily.

By this method one can learn what particular lot
of milk among several is responsible for undesirable
fermentations. Moreover, having traced the source of
contamination to a single herd of cows, it is easily

43^ SCIENCE AND PRACTICE OF CHEESE-MAKING

possible, by applying the test to single cows, to ascer-
tain which individual or individuals may be the source
of trouble.

Precautions. — Two points must be carefully ob-
served in carrying out this test: (i) The tempera-
ture must be kept as near 98° F. as possible, in
order that the bacteria may develop as desired.
This can be done by keeping the temperature of the
water surrounding the jars at 100° to 102° F. The
temperature must be watched. (2) The thermometer
and the knife used should be made. not only clean but
sterile each time after using in one sample before
placing them in another.

TEST FOR SPECIFIC GRAVITY AND
SOLIDS OF MILK

^'Milk Testing, etc., pp. 127-132)

Process of using Quevenne lactometer. — The

sample of milk to be tested for specific gravity is
brought to a temperature between 50° and 70° F. For
convenience the milk is placed in a cylinder, which
is nearly filled. The lactometer is carefully lowered
into the milk until it floats and is allowed to re-
main half a minute or more. Then one reads and
records (i) the point at which the lactometer scale
comes in contact with the upper surface of the milk;
and (2) the temperature. The lactometer reading is
then corrected, if the temperature is above or below
60° F. For example, the lactometer settles in milk,
which is at a temperature of 65° F., to the point
marked 29. Adding to the reading for correction o.i
for each degree above 60° F., which in this case is 0.51

TESTS USED IN CHEESE-MAKING 439

the reading becomes 29.5. This means that the spe-
cific gravity is 1.0295. If the temperature of the
milk were 55° F., the correction is subtracted and
the reading becomes 28.5, equal to specific gravity
[.0285.

Babcock's formulas for solids and solids-not-fat. —
The following formulas were devised by Dr. Bab-
cock:

(i) Formula for determining solids-not-fat. — Sol-
ids-not-fat=^L-j-o.2f, in which L is the reading of
the Ouevenne lactometer and f is the per cent of fat
m the milk.

(2) Formula for determining solids in milk. —
Total solids=)4L+i-2f.

These formulas can be expressed in the form of
rules as follows :

Ride I. — To find the per cent of solids-not-fat in
milk, divide the reading of the Quevenne lactometer
by 4, and to the result add the number giving the per
cent of fat in the milk multiplied by 0.2.

Rule 2. — To find the per cent of solids in milk, di-
vide the Quevenne lactometer reading by 4, and to
the result add the number giving the per cent of fat
multiplied by 1.2.

THE HOT-IRON TEST

This test is used for the purpose of ascertaining
when to remove whey from curd and when to mill
curd. An iron of convenient size and length for hold-
ing, as a half-inch gas-pipe, is heated fairly hot at one
end. The iron is carefully wiped with a cloth until
it is clean and smooth. A handful of curd is then
taken and placed in dry cloth and squeezed by the

440 SCIENCE AND PRACTICE OF CHEESE-MAKING

hand, until the surface has been well dried. The curd
is then gently pressed against the portion of the iron
where it is hot enough to make the curd stick to
the iron but not hot enough to scorch it. The curd is
then carefully drawn away from the iron and, if in
proper condition, produces fine, silky threads, the
length of which depends upon the amount of acidity
of the curd.

VOLUMETRIC TEST FOR CASEIN

A new test for casein has been recently worked out
at the New York experiment station by Van Slyke and
Bosworth (Technical Bulletin No. lo, Sept., 1909). In
outline the method is as follows : Into a 200 cc. flask
one measures 17.5 cc. (18 grams) of milk, adds about
80 cc. of water and i cc. of phenolphthalein, after which
a solution of sodium hydroxid (caustic soda) is added
until the mixture is neutral. Standardized acetic acid
is then added until the casein is completely precip-
itated, the volume of the mixture is made up to 200 cc.
by addition of water and then filtered. Into 100 cc.
of the clear filtrate, a standardized solution of sodium
hydroxid is run until neutral. The solutions are so
standardized that i cc. is equivalent to i per cent of
casein in the milk examined. Therefore, the number
of cc. of standard acid used, divided by 2, less the
amount of standard alkali used in the final titration
gives the percentage of casein in the milk. The opera-
tion usually requires 12 to 15 minutes when apparatus
and solutions are at hand in convenient form ready for
use ; several determinations can be carried on at the
same time with much relative economy of time.

TESTS USED IN CHEESE-MAKING 44I

Apparatus. — (i) Two 50 cc. burettes, accurately
graduated to one-twentieth cc. Automatic burette
fillers save much time in making many determinations.

(2) Flasks, so-called volumetric, holding 200 cc.
and accurately marked. Flasks having necks 43^ to 5
inches long and ^-inch inside diameter are desirable
for greatest convenience.

(3) Pipette (Babcock test form), accurately grad-
uated to deliver 17.5 cc. (18 grams) of milk.

(4) Pipette graduated to deliver 100 cc.

(5) Pipette graduated to deliver about i cc. and
provided with a rubber bulb (so-called dropper).

(6) Cups, plain white, holding 200 cc. or more.

(7) Funnels, glass or granite-ironware, 3 to 4
inches in diameter.

(8) Filter-papers cut round, 6 to 7 inches in diam-
eter; or fine linen filters cut to proper size and shape,
which can be washed after use and used repeatedly.

(9) Measuring-cylinders, accurately graduated and
holding 1,000 cc.

Solutions. — (i) Sodium hydroxid (caustic soda).
This solution may be made most conveniently by pre-
paring a regular tenth-normal solution in the manner
recommended by Publow (p. 427), and then diluting
795 cc. of this to one liter (or one may directly dilute
the 50 cc. of concentrated alkali to 2,900 cc). In
such a solution i cc. corresponds to 0.09 gram of casein
(or I per cent). In making standard solutions, pure
distilled water should be used if possible, or else as
pure rain-water as can be obtained. Alkali solutions
must be kept in tightly-stoppered bottles to prevent
loss of strength. ''Alkaline tablets" cannot be used
for the casein test.

442 SCIENCE AND PRACTICE OF CHEESE-MAKING

(2) Acetic acid. — This solution is so made that a
given amount of it will exactly neutralize the same
amount of the standard alkali solution of the strength
above indicated. The simplest way of preparing this
solution is to purchase a normal solution and dilute
100 cc. of this to 1,260 cc. To prevent fermentation of
dilute acetic acid and consequent change of strength on
long standing, it is desirable to add a small amount of
pure mercuric chlorid (corrosive sublimate) and to
keep the solution in tightly-stoppered bottles.

(3) Phenolphthalein solution. — This is made by
dissolving one gram of the dry, powdered compound in
100 cc. of 50 per cent alcohol and adding to the pre-
pared solution one or more drops of dilute alkali until
the solution is very slightly pinkish in color.

Performing the test. — (i) Measuring and diluting
sample of milk. The milk to be tested is well mixed
and a 17.6 cc. pipette filled to the mark and the milk
run into a 200 cc. flask. Then add about 80 cc. of
pure, soft water (preferably, distilled).

(2) Neutralizing the milk. — Add i cc. of phenol-
phthalein solution to the dilute milk and then run into it
the alkali solution from a burette, in small portions,
shaking vigorously after each addition of alkali, until
a faintly, but distinctly, pinkish shade of color remains
even after considerable agitation. Marked excess of
alkali must be avoided.

(a) Preparation of a color-standard. — More satis-
factory results in neutralizing can be obtained by pre-
paring a color-standard for comparison. This can be
prepared as follows : About 20 cc. of fresh skim-milk
and 80 cc. of water are put into a 200 cc. flask and a
very small amount of pure corrosive sublimate added
to prevent souring. A few drops of ordinary carmine

TESTS USED IN CHEESE-MAKING 443

ink are considerably diluted with water and this is
carefully added, a few drops at a time, to the diluted
skim-milk until a faint but distinct pinkish coloration
appears. This can be more readily perceived by plac-
ing beside the flask another flask half full of uncolored
diluted skim-milk. The coloration must be as slight
as possible and yet be appreciably distinct when com-
pared with uncolored milk. After the color-standard
has been prepared, the flask is stoppered. It is well to
keep this standard in a dark place when not in use.
With some carmine colors, the pinkish shade in the
milk deepens on standing, especially when exposed to
light, and with others it may fade. If any deepening
of color is observed at any time, addition of dilute
skim-milk will reproduce the proper shade; in case of
fading, the addition of one or more drops of carmine
ink is called for. Skim-milk is used because, in case
of normal milk, the fat separates on standing, adheres
to the sides of the flask, and obscures the color.

(b) Use of color-standard. — In neutralizing a
sample of milk, the color-standard is placed beside the
sample under examination for constant comparison
after each addition of alkali. The flasks should be
placed on a white surface and in a good light. In fresh
milks, it is usually found that 3 or 4 cc. of alkali is
sufficient to neutralize the milk. One can add 2 or 3
cc. of alkali at the start and then add it in smaller por-
tions, until the milk begins to show signs of neutrality,
after which the alkali is added drop by drop.

(3) Precipitation of casein.- — (a) Addition of acid.
Into the neutralized sample of diluted milk, which
should be at a temperature of 65° to 75° F., one now
runs from a burette some of the standardized acetic
acid, adding the acid approximately in 5 cc. portions

444 SCIENCE AND PRACTICE OF CHEESE-MAKING

and shaking vigorously for a few seconds after each
addition. It is usually safe to add about 25 cc. of acid
before examining the milk to see if the casein separates
in the form of white flakes. After adding 20 to 25
cc. and shaking, the mixture is allowed to stand still.
If enough acid has been added, the casein separates
promptly in large, white flakes, and on standing a
short time the liquid above the settled casein appears
clear and not at all milky. If the addition of 25 cc.
of acid is insufficient, add i cc. more of acid and shake ;
continue the addition of acid i cc, at a time, until the
casein is observed to separate promptly and completely
on standing at rest for a short time. The number of
cc. of acid used to effect precipitation is noted and this
result is recorded as A.

(b) Influence of temperature. — For convenience of
work and uniformity of results, the temperature of the
mixture at the time of the addition of acid may be be-
tween 65° and 75° F. Under these conditions, many
milks give satisfactory results with just 30 cc. of acid.
In case of milks containing 3.5 to 4 per cent of casein,
one may need to use as much as 35 to 40 cc. of acid.
Rarely has it been found that 25 cc. of acid is ex-
cessive. The amount of acid may be 2 or 3 cc. in ex-
cess of that required to effect complete precipitation
without seriously affecting the accuracy of the results,
provided the temperature of the mixture is below
75° F. At temperatures above 75° F., good results are
attainable, but care must be taken not to use much
excess of acid; and, of course, the higher the temper-
ature, the less will be the amount of acid required. In
working at temperatures under 65° F., the casein sepa-
rates more slowly or requires more acid to separate
promptly. When working with milk that is much

TESTS USED IN CHEESE-MAKING 445

below 65° F., it is well to use for dilution water that
is at a temperature of about 80° F.

(4) Filtration of casein. — After the casein is com-
pletely precipitated, one adds pure, soft (preferably,
distilled) water to the flask until the 200 cc. mark is
reached. The flask is then vigorously shaken 10 or 15
seconds, in order to distribute the acid through the
mixture as uniformly as possible. The contents of the
flask are then poured on a clean, dry filter, and the
filtrate caught in a cup. The funnels, filter and cups
used to catch filtrate should all be dry before being
used. It is well, generally, to allow the filtration to
continue until practically all of the liquid has run into
the cup.

(a) Rapidity of filtration. — The usual time of filtra-
tion should not exceed 3 to 5 minutes. The rapidity
depends upon the temperature of precipitation and the
completeness of the separation of casein. In general,
the higher the temperature of the mixture when pre-
cipitated with acid, the more rapid should be filtration,
other conditions being uniform. In case of insufficient
acid, the filtration is slower.

(b) Appearance of filtrate. — The filtrate should
be quite clear, though this is not always a sure indica-
tion that the right amount of acid has been used.
Sometimes the filtrate may be clear when not quite
enough acid has been used, in which case the filtration
is apt to be slow. In case of milk rich in fat, a slight
turbidity may appear, due to fat-globules in the filtrate.
The filtrate should be free from all marked signs of
turbidity or anything like milkiness. If such a filtrate
appears, a new sample of milk should be taken and
the operation repeated from the beginning, more acid
being used than before. With a little experience,

446 SCIENCE AND PRACTICE OF CHEESE-MAKING

especially under proper instruction, no difficulty should
be found in recognizing quickly when the casein is
separated so as to give satisfactory results.

(5) Titration zvith alkali. — After filtration is com-
pleted, one measures 100 cc. of the filtrate with the
pipette into a cup and then runs into this from the
burette the standard alkali until a faint but distinct
pink color remains clearly marked throughout the
solution for half a minute or longer before beginning
to fade. The number of cc. of alkali used is noted and
this result is recorded as B.

The last portions of the alkali must be added care-
fully, a drop at a time, agitating the mixture well after
each addition. The exact neutral point is not perfectly
sharp on account of the presence of phosphates, and
the appearance of the desired coloration is, therefore,
not as sudden and pronounced as might be desired.
With experience one should have no difficulty in get-
ting within one drop of the correct amount of alkali.
The chief precaution to be observed is to have the same
shade and duration of color every time. Thus, one
should not in one titration add alkali until a deep pink
coloration appears, lasting for some minutes, and in
another a coloration that disappears within 5 seconds.
In the case of milk rich in phosphates, the solution
usually grows quite turbid as the neutral point is ap-
proached, making it necessary to use more care in ob-
serving the color of the end-point of the reaction.

If one desires to make a second titration of the same
filtrate, one can use 50 cc. of the remaining portion,
multiplying the result by 2 and recording this as B.

(6) Calculation of results. — The calculation of the
percentage of casein from (i) the amount of acid
used (A) in precipitating casein and (2) the amount

TESTS USED IN CHEESE-MAKING 44/

of alkali used (B) in neutralizing lOO cc. of filtrate
is very simple. Divide A by 2 and from the result sub-
tract B; or, expressed as a formula,

B=per cent of casein in milk.

Example: One used 30 cc. (A) of acid in precip-
itating casein and 11.95 cc (B) of alkali in neutraliz-
ing 100 cc. of filtrate (one-half of filtrate from the
casein precipitate corresponding to 9 grams of milk).
Substituting 30 for A and 11.95 for B in the formula,
we have

^ — 11.95 ( = 15 — ii.95)=3-05 (the percentage of
^ casein in milk).

(7) Use of preservatives. — In making a casein de-
termination by this method, it is desirable, when possi-
ble, to use milk not more than 24 hours old, which has
been kept in a cool place. Milk which is sour or which
coagulates on heating cannot be used with satisfac-
tory results. However, by adding to fresh milk pure,
powdered mercuric chlorid (corrosive sublimate) in
the approximate proportion of i part to 1,000 or 1,500
parts of milk, and then keeping mixture at a tempera-
ture of 50° or lower, one can obtain satisfactory re-
sults with milk that has been kept two or three weeks.
Milk thus treated should be shaken often enough to
keep the fat well incorporated in the body of the milk.
The desired amount of mercuric chlorid may be ap-
proximately measured by taking for one quart of milk
the amount of mercuric chlorid that will lie easily on
the surface of a silver dime, or, more conveniently,
the amount held by a 0.22-inch pistol cartridge-shell,
one-half inch long, when loosely filled. Commercial

44^ SCIENCE AND PRACTICE OF CHEESE-MAKING

mercuric chlorid tablets containing coloring-matter
cannot be used.

(8) Summary of precautions. — Assuming that the
graduated glassware is accurate and the standardized
solutions of correct strength, the following special
points are to be observed with care in making test.

(a) Preliminary neutralization. — In neutral'zing
the sample of milk, excess of alkali must be avoided,
which can be controlled by the use of a properly pre-
pared color-standard.

(b) Conditions of precipitation. — Before precip-
itating with acid, have the dilute, neutralized milk at
a temperature between 65° and 75° F. Add enough
acid to cause the casein to separate promptly in large
flakes, leaving the supernatant liquid clear. Shake the
mixture vigorously at intervals during the addition
of acid ; also after complete precipitation and again
after dilution to 200 cc. mark.

(d) Titration with alkali. — In titrating the filtrate
with alkali, avoid an excess of alkali. Add the alkali
solution cautiously until, after thorough agitation, a
faint but distinct pink color remains through the solu-
tion half a minute or longer. The same uniform shade
and duration of pink color should be obtained as nearly
as possible in all cases.

(e) Acid milk. — Milk that is sour or that coag-
ulates on heating should not be used.

(f) Use of preservatives. — Milk treated, when
fresh, with a small amount of pure powdered mercuric
chlorid (corrosive sublimate) and then kept in a cool
place gives good results for two or three weeks.

TESTS USED IN CHEESE-MAKING 449

CENTRIFUGAL TEST FOR CASEIN .

The following centrifugal method has been worked
out at the Wisconsin station by Hart :

Apparatus and reagents. — (i) Testing-tube, with
neck so graduated that each division represents 0.20
per cent when one uses 5 cc. of milk. (2) Centrifuge,
of special form, run by hand, having a wheel 15 inches
in diameter and geared to give a speed of 2,000 revo-
lutions a minute. (3) Pipette for measuring 5 cc. of
milk. (4) Cylinder for measuring 2 cc. of chloroform.
(5) Dilute acetic acid containing 0.25 per cent of
acetic acid, prepared by diluting 10 cc. of glacial acetic
acid (99.5 per cent) to 100 cc. with water, and then
diluting 25 cc. of this solution to one liter. (6) Chloro-
form of the best quality.

Method of operating test. — In a testing-tube one
puts 2 cc. of chloroform, then on top of this 20 cc.
of the dilute (0.25 per cent) acetic acid. One then
runs in 5 cc. of milk (65° to 75° P.), after which the
thumb is placed over the opening of the tube and the
tube inverted to bring the mixture into the barrel-
shaped portion of the tube; then the whole is shaken
with a fair degree of vigor for 15 or 20 seconds, ac-
curately timed with watch before one. In the shaking
process, the chloroform takes up most of the fat and
the acid precipitates the casein in fine particles. The
sample is then ready for the centrifuge and should be
whirled within 30 minutes. The centrifuge is closed
before whirling and is brought to a speed of 2,000
revolutions a minute, after which it is run at this rate
yYz to 8 minutes. This must be done with such pre-
cision that it is important to use a metronome during
the operation. After whirling, the testing-tubes are

450 SCIENCE AND PRACTICE OF CHEESE-MAKING

removed and placed in a rack in an upright position
and then read after lo minutes or more. The chloro-
form and fat should be at the bottom and on top of
this a white, cylindrical mass of casein. The end
surfaces of this casein cylinder, which should be flat,
are read on the scale directly, the result being the
per cent of casein in the milk, if the test is successful.
While fresh milk is desirable for best results, it is said
that seven-day composite samples may be used by
taking one-ounce samples of milk each day in a brown
or amber-colored glass receptacle, adding on the first
day and again on the third day one-fourth of an or-
dinary potassium bichromate tablet (equal to i^ or
2 grains). The mixture is gently agitated daily by a
rotary motion, and kept well stoppered in a dark, cool
place.

Conditions affecting accuracy of results. — (i) Use
of sour milk. (2) Use of milk containing preserva-
tives, except bichromate. (3) Too strong or too dilute
solution of acetic acid. (4) Poor quality of chloro-
form. (5) Temperature of acid and milk below 65°
or above 75° F. (6) Shaking mixture of acid, chloro-
form and milk too short or too long a time, too hard or
not hard enough. (7) Allowing shaken mixture to
stand too long before whirling. (8) Running centri-
fuge too slow or too fast, or for a longer or shorter
time than 7^ or 8 minutes. (9) The use of a revolv-
ing wheel greater or less than 15 inches without a cor-
responding change in the number of revolutions. ( 10)
Reading the results in less than 10 minutes after whirl-
ing. (11) Any condition which disturbs the distinct
flatness of the upper or lower surface of the cylindrical
column of compacted casein.

CHAPTER XXIX

Cheese-Factory Management

STATEMENT FOR PATRONS

Whenever a dividend is made, each patron should
receive with the dividend a statement containing all
necessary items, which will enable each patron to
calculate the dividend and satisfy himself that no
errors have been made. It is convenient to use a
printed blank form for making such statements to
patrons. The form given below is suggested as cov-
ering all important points, but one much simpler may
usually answer the purpose. It is also highly de-
sirable that a general statement be issued at the close
of the season, giving a summary of the whole season's
work.

Statement of Cheese-
Factory.

1. Name of patron

2. Statement for month of (or whatever the period of time is) 19....

3. Sales include dates from to

4. Number of pounds of cheese in sale (or sales)

5. Number of pounds of milk represented in sale (or sales)

6. Amount of money received $

7. Price received per pound for cheese (at each sale, and average if more

than one) cents

8. Expenses deducted $

9. Balance for dividends $

10. Net value of one pound of milk (weight-of-milk basis) cents

11. Number of pounds of milk delivered by you

12. Value of milk delivered by you $

13. Total number of pounds of milk-fat represented in sale (when fat

basis is used)

14. Average per cent of milk-fat in miik per cent

15. Net value of one pound of milk-fat cent?

451

452 SCIENCE AND PRACTICE OF CHEESE-MAKING

16 Average per cent of milk fat in milk delivered by you

17. Number of pounds of milk fat delivered by you

18. Value of milk-fat delivered by you

19. Debtor by pounds of cheese at cents per pound.

20. Money due you

21. Number of pounds of cheese made from 100 pounds of milk

22. Number of pounds of milk required to make one pound of cheese

23- Number of pounds of cheese" made for one pound of fat in milk

BUSINESS MANAGEMENT OR ORGANIZA-
TION OF A CHEESE-FACTORY

The business management of a cheese-factory is
generally carried on according to one of two sys-
tems ; in one case the ownership of the factory is
private, while, in the other, it is vested in a stock
company.

In the case of private ownership of the cheese-
factory, the owner receives a certain price per
pound for making the cheese and is responsible
for all expenses connected with the operations of
cheese-making. The milk and cheese are regarded
as the property of the patrons and they have some
organized arrangement for selling the cheese and
distributing the money. In some cases where the
ownership of the factory is private, the milk is
contracted for at a certain price and then the
patrons have nothing to do with the business man-
agement.

When a cheese-factory is owned by a stock-com-
pany, the patrons are the stockholders. They form a
definite organization and through chosen officers carry
on the entire business management from the hiring of
a cheese-maker to the sale of the cheese.

Preliminary steps in establishing a co-operative
cheese-factory. — When a community is considering
the question of organizing a stock-company for the

CHEESE-FACTORY ORGANIZATION 453

purpose of building- and running a cheese-factory,
the first point to be ascertained is the number of
cows which can be utihzed as a source of milk sup-
ply. This information can be gained only by a
careful personal canvass. In general, it may be
said that no attempt should be made to establish
a factory unless at least 150 cows within a radius
of 3 or 4 miles can be relied upon to furnish milk.
Dairymen should be on their guard against so-
called factory ''sharks," a name applied to repre-
sentatives of supply houses who make a business
of promoting co-operative factories and creameries.
The promoter makes exaggerated representations
of the profits of cheese-making for dairymen with-
out reference to the number of available cows.
When he is successful in persuading farmers to
organize a company, he attends to the building and
equipment, turning over the plant to the farmers at
a price which nets him one to two thousand dollars.
Before erecting a cheese-factory, inquiry for plans
and cost should be made of the state department of
agriculture or of the nearest agricultural college.
In general, it will be found safe and profitable to
have nothing whatever to do with any traveling
agents.

Formation of a cheese-factory company or as-
sociation.— After a successful canvass has been
made and there have been obtained signed agree-
ments to furnish milk from a certain number of
cows, on the part of those who intend to join the
association, a meeting should be called for organi-
zation. The money may be raised either by indi-
vidual pledges to purchase a certain number of

454 SCIENCE AND PRACTICE OF CHEESE-MAKING

shares of stock at a certain price ; or an elected board
of directors may be authorized to borrow the amount
of money needed, the debt being discharged by taking
a fixed proportion from the dividends of the associa-
tion members.

Articles of agreement or constitution and by-
laws.— When it has been decided to form a cheese-
factory association, it is necessary to prepare an
agreement to be signed by all the members; this
agreement embodies the details of organization,
usually in the form of a constitution and by-laws.
Different conditions will call for differences in the
details of such an agreement. Suggestions can be
given here, but they will need modification and
adaptation to suit the conditions peculiar to each
association.

( 1 ) Name and object. — This association shall

be known as the Cheese-Factory

Co-operative Company; its object is to manufac-
ture cheese from normal (whole) milk. The
undersigned agree to become members of said com-
pany.

(2) Capital stock. — The capital stock of the com-
pany shall be $ , divided into

shares of $ each.

(3) Officers. — The officers of the company shall
be a president, a secretary and a treasurer, and
these, with three other members of the company,
shall constitute a board of directors. These offi-
cers shall be elected by ballot at the annual meet-
ing and shall hold office one year or until their
successors have been elected and qualified. 'Vacan-
cies in the board may be filled by the directors

CHEESE-FACTORY ORGANIZATION 455

for the time ensuing until the next annual election.
(4) Duties of officers. — (i) The president
shall preside at all meetings of the company and
of the board; in his absence, some other member
of the board shall preside. He shall perform such
other duties as may be indicated. All documents,
drafts, etc., involving the interests of the com-
pany, shall be signed by the president. He shall
call special meetings when necessary. (2) The
secretary shall keep an accurate record of all pro-
ceedings of the meetings of the company and of
the board. He shall issue notices of meetings, ap-
pointments on committees, statements to patrons,
etc. ; he shall sign all papers, carry on the cor-
respondence, etc. (3) The treasurer shall receive
and disburse the money of the company. He shall
give receipt for all money belonging to the asso-
ciation. He shall make out dividends, etc. He
shall pay out money only upon orders signed by
the president and secretary. He shall keep a cor-
rect financial account between the company and
its members. He shall keep a proper set of books,
which shall be open for inspection to members of

the company. He shall give bonds for $

(4) The board of directors shall elect one of their
number as general business manager of the com-
pany, who shall be responsible for the conduct of
the business details of the company. The board
shall appoint any needed agents, manage the com-
pany's investments, audit all accounts and fix com-
pensation for services in all cases. They shall make
regulations and enforce them. They shall arrange
for the keeping of a record of all necessary details.

456 SCIENCE AND PRACTICE OF CHEESE-MAKING

such as weights of milk deHvered daily by each
member, fat-test of the same, the amounts of cheese
made day by day, the sales of cheese, current ex-
penses, etc. They shall distribute monthly among
the members or patrons the money due them.
They shall make a complete statement at the annual
meeting covering for the year all matters relating to
the business of the company. Meetings of the board
may be called by the president or by any two of its
members.

(5) Meetings. — The regular annual meetings of
the company shall be held on the first Tuesday of
the month of Special meet-
ings may be called by the president or on written
request of ten members of the company. Written
notices for all special meetings must be sent to
each member of the company three days in advance
of such meeting. In addition to the election of
officers and presentation of reports, the members
shall decide by majority vote at the annual meeting
in what manner the dividends shall be made (weight-
of-milk, fat-basis, etc.).

(6) Regulations. — The following are samples of
what regulations may be made: (a) The price for

making cheese shall be cents a pound.

(b) Members shall be held responsible for furnish-
ing milk from the number of cows promised, (c)
The cheese-maker may reject such milk as is
tainted or of too high acidity or is any way un-
suited to make high-grade cheese, (d) Milk must
not be received unless it has been properly strained
and delivered at the factory at a temperature not
above degrees F. (e) The milk of each

CHEESE-FACTORY ORGANIZATION 45/

patrons shall be tested for its percentage of fat not
less often than once in lo days, (f) A testing-com-
mittee consisting of the secretary or treasurer, one
other director and one member not an officer shall
assist the cheese-maker in testing the milk, (g) A
patron's premises may be inspected by order of
the board to ascertain the suitability of the conditions
for producing and caring for clean milk. The board
may order samples of milk taken at patron's farm
when desired, (h) No patron shall, in any manner,
adulterate milk to be taken to the factory, as by water-
ing, skimming, addition of preservative, etc. No

patron shall take more than pounds of whey for

lOO pounds of milk delivered.

(7) Voting pozver. — Members may, at all meet-
ings of the company, be entitled to one vote for each
1,000 pounds of milk furnished by him during the
preceding season or during the preceding portion of
the current season, as shown by the records ; or each
may have one vote for each share of stock owned by
him.

(8) Amendments. — Any changes or amendments
to the constitution or by-laws may be made in writing
and posted conspicuously in the cheese-factory one
month previous to action upon them. Two-thirds vote
of the stockholders is required to make such changes.

CHAPTER XXX

The Literature of Cheese-Making

It is desirable to give references to the literature
of cheese-making for the benefit of those who wish
to go to original sources of information. In pre-
paring the list given below, the aim is mainly to
cover the ground represented in the subject-matter
of the book. A selection has been made of what
may be regarded as the most useful material for
this purpose, no attempt being made to present
an exhaustive list of everything written on the
subject.

In order to render the material most readily
available for reference, the following plan is
adopted : There is first given a continuously
numbered list of the publications referred to; the
arrangement is, first, by institutions and then
under each the individual articles are given in
chronological order. Then follows an index of
the subjects treated in this list of publications.
It is believed that this plan will prove the most
useful in enabling anyone to consult the literature.

PUBLICATIONS RELATING TO CHEESE-MAKING
Cornell University Experiment Station, Ithaca, N. Y.

1 1st Ann. Rept. (1879-80). Experiments upon the cur-
ing of cheese (pp. 9-27). Babcock.

2 Bui. 85 (March, 1895). Whey-butter. Wing.

3 Bui. 158 (Jan., 1899). Sources of gas and taint-
producing bacteria. Moore and Ward.

4 Bui. 178 (Jan., 1900). The invasion of the udder by
bacteria. Ward.

5 Bui. 203 (July, 1902). The care and handling of
milk. Htinziker.

458

THE LITERATURE OF CHEESE-MAKING 459

Iowa Agricultural College Experiment Station, Ames, Iowa

6 Bui. 21 (1893). Investigations in cheese -making
(pp. 751-767). Wallace.

7 Bui. 24 (1894). Changes during cheese -ripening (pp
969-984). Patrick.

8 Bui. 57 (1901). Experiments in curing cheese.
McKay.

Michigan State Agricultural College Experiment Station,

East Lansing, Mich.

9 Special Bui. 16 (June, 1902). Aeration of milk.
Marshall.

10 Special Bui. 21 (Sept., 1903). Cheese problems:
(a) Relation of yield of cheese and per cent of fat in milk.
(6) Paraffining cheese, (c) Cheddar vs. stirred curd, (d)
Cheese-ripening as affected by temperature and moisture.
(e) Sage cheese, (f) Gassy milk. Michels.

11 Special Bui. 23 (Jan., 1904). A preliminary note on
the associative action of bacteria in the souring of milk and
in other milk fermentations. Marshall.

12 Special Bui. 29 (May, 1904). Additional work upon
the associative action of bacteria in the souring of milk and
in other milk fermentations. Marshall.

13 Special Bui. ?)Z (June, 1905). Extended studies of
the associative action of bacteria in the souring of milk.
Marshall.

14 Special Bui. 42 (March, 1908). Bacterial associa-
tions in the souring of milk. Marshall.

15 Bui. 183 (June, 1900). Gassy curd and cheese.
Marshall.

16 Bui. 201 (June, 1902). Aeration of milk. Marshall.

Minnesota Agricultural Experiment Station, St. Anthony Park,

Minnesota

17 Bui. 19 (Jan., 1892). Experiments in cheese -mak-
ing. Incorporating cream into cheese (pp. 20-25). Snyder.

18 Bui. 27 (Feb., 1893). Losses of milk-solids in cheese-
making (pp. 57-62). Snyder.

19 Bui. 35 (Oct., '1894). Manufacture of sweet-curd
cheese. Haecker.

New York Agricultural Experiment Station, Geneva, N. Y.

20 Bui. 37 (Nov., 1891) and 10th Ann. Rept. (pp. 220-
299). Investigation of cheese : (a) Experiments in the manu-
facture of cheese, (h) Influence of composition of milk on
composition and yield of cheese, (c) A study of the process
of ripening of cheese. Van Slyke.

460 SCIENCE AND PRACTICE OF CHEESE-MAKING

21 Bui. 43 (June, 1892). Experiments in the manu.
facture of cheese during May. Van Slyke.

22 Bui. 45 (Aug., 1892). Experiments in the manu-
facture of cheese during June. Van Slyke.

23 "Bui. 46 (Sept., 1892). Experiments in the manu-
facture of cheese during July and August. Van Slyke.

24 Bui. 47 (Nov., 1892). Experiments in the manu-
facture of cheese during September and October. Van Slyke.

25 Bui. 50 (Jan., 1893) and 11th Ann. Rept. (pp. 299-
467). Summary of the results of experiments made in the
manufacture of cheese during the season of 1892. Van Slyke

26 Bui. 54 (May, 1893) and 12th Ann. Rept. (pp. 276
319). Experiments in the manufacture of cheese: Part 1
Manufacture of cheese from normal milk rich in fat. Part II,
Study of cheese-ripening process. Van Slyke.

27 Bui. 56 (May, 1893) and 12th Ann. Rept. (pp. 244-
275). Experiments in the manufacture of cheese: Part I,
The manufacture of Edam cheese. Part II, The manufacture
of Gouda cheese. Van Slyke.

28 Bui. 60 (Oct., 1893). Investigation relating to the
manufacture of cheese. Part I, Results of work done in the
No. 1 factory of E. L. Stone at Mannsville, Jefferson Co.,
during the season of 1893. Van Slyke.

29 Bui. 61 (Nov., 1893). Investigation relating to the
manufacture of cheese. Part II, Results of work done in the
factory of G. Merry at Verona, Oneida Co., N. Y., during the
season of 1893. Van Slyke.

30 Bui. 62 (Dec, 1893). Investigation relating to the
manufacture of cheese. Part III, Results of Work done
during the season of 1893 in 48 different factories, located
in 8 different counties. Van Slyke.

31 Bui. 65 (Jan., 1894) and 12th Ann. Rept. (pp. 319-
486). Investigation relating to the manufacture of cheese.
Part IV, Summary of the results of work done in cheese-
factories during the seasons of 1892-3. Van Slyke.

32 Bui. 68 (March, 1894). Investigation relating to
the manufacture of cheese. Part V, Fat in milk as a practical
basis for determining the value of milk for cheese -making.
Van Slyke.

33 Bui. 71 (May, 1894). Some reasons why there
should be a legal standard for cheese in New York state.
Van Slyke.

34 Bui 79 (Nov., 1894) and 13th Ann. Repl (pp. 351-
379). Comparison of different breeds of -:attle. The cost of
cheese production- Van Slyke-,

THE LITERATURE OF CHEESE-MAKING 461

35 Bui. 82 (Dec, 1894) and 13th Ann. Rept. (pp. 452-
522). Results of investigation relating to the manufacture
of cheese for the season of 1894, Van Slyke.

36 Bui. 105 (Aug., 1896) and 15th Ann. Rept. (pp. 37-
65). Effects of drouth upon milk and cheese production.
Van Slyke.

37 Bui. 110 (Oct., 1896) and 15th Ann. Rept. (pp. 66-
106). Milk-fat and cheese yield. Van Slyke.

38 Bui. 183 (Dec, 1900) and 19th Ann. Rept. (pp. 29-
51). Notes on some dairy troubles: (a) Flavor in milk and
its products, {b) Fishy flavor in milk, {c) Bitter flavor in
Neufchatel cheese. {d) Sweet flavor in cheddar cheese.
{e) Rusty spot in cheddar cheeee. Harding, Rogers and
Sfntth •

39 Bui. 184 (Dec, 1900) and 19th Ann. Rept. (pp. 251-
260). The influence of the temperature of curing upon the
commercial quality of cheese. Smith.

40 Bui. 203 (Dec, 1901) and 20th Ann. Rept. (pp. 165-
193). A study of enzyms in cheese. Van Slyke, Harding
and Hart.

41 Bui. 207 (Dec, 1901) and 20th Ann. Rept. (pp.
194-219). Conditions affecting weight lost by cheese in cur-
ing. Van Slyke.

42 Bui. 225 (Dec, 1902) and 21st Ann. Rept, (pp. 27-
53). Control of rusty spot in cheese-factories, Harding and
SfyittJi.

43 Bui. 231 (Feb., 1903) and 22d Ann. Rept. (pp. 165-
187). The relation of carbon dioxid to proteolysis in the
ripening of cheddar cheese. Van Slyke and Hart.

44 Bui. 233 (June, 1903) and 22d Ann. Rept. (pp. 188-
217), Rennet enzym as a factor in cheese-ripening. Van
Slyke, Harding and Hart.

45 Bui. 234 (July, 1903) and 22d Ann. Rept. (pp. 218-
242). Experiments in curing cheese at different tempera-
tures. Van Slyke, Smith and Hart.

46 Bui. 236 (July, 1903) and 22d Ann. Rept. (pp. 243-
273). Conditions affecting chemical changes in cb ^ese-
ripening. Van Slyke and Hart.

47 Bui. 261 (Jan., 1905) and 24th Ann. Rept. (pp. 238-
271). Some of the relations of casein and paracasein to bases
and acids and their application to cheddar cheese. Van
Slyke and Hart.

48 Technical Bui. 3 (Dec, 1906) and 25th Ann. Rept.
(pp. 203-286). I, The action of dilute acids upon casein
when no soluble compounds are formed. II, The hydrolysis
of the sodium salts of casein. Van Slyke (L. L.) and Van
Slyke {D. D.).

462 SCIENCE AND PRACTICE OF CHEESE-MAKING

49 Technical Bui. 4 (April, 1907). I, Some of the first
chemical changes in cheddar cheese. II, The acidity of the
water-extract of cheddar cheese. Van Slyke and Bosworth,

50 Technical Bui. 6 (Dec, 1907). Chloroform as an
aid in the study of milk-enzyms. Harding and Van Slyke.

Oregon Agricultural Experiment Station, Cornwallis, Ore.

51 Bui. 78 (March, 1904). Canning cheese. Pernot.

U. S. Department of Agriculture, Bureau of Animal Industry,
Dairy Division, Washington, D. C.

52 Bui. 11 (Nov., 1895) and 55 (Feb., 1903). Statistics
of the dairy. Alvord.

53 Bui. 15 (Oct., 1896). The cheese industry of the
state of New York. Gilbert.

54 Bui. 17 (Nov., 1896). Dairy schools. Pearson,

55 Bui. 49 (June, 1903). The cold-curing of cheese.
Report upon experiments conducted under the auspices of
the U. S. Department of Agriculture, Bureau of Animal In-
dustry, Dairy Division, in co-operation with the Wisconsin
Agricultural Experiment Station and the New York Agri-
cultural Experiment Station. Alvord.

56 Evil. 62 (July, 1904). The relation of bacteria to
the flavors of cheddar cheese. Rogers.

57 Bui. 75 (Sept., 1905). Records of dairy cows in the
United States. Lane.

58 Bui. 83 (March, 1906). The cold storage of cheese.
Lane.

59 Bui. 85 (May, 1906). The cold-curing of American
cfieese. Doane.

60 Bui. 105 (Jan., 1908). Varieties of cheese: descrip-
tions and analyses. Doane and Lawson.

61 Bui. 110 (Nov. 1908). Development of lactic acid
in cheddar cheese-making. Doane. ,

Utah Agricultural Experiment Station, Logan, Utah

62 Bui. 73 (Aug., 1901). Experiments in cheese-mak-
ing (pp. 41-54). Lin field.

63 Bui. 96 (March, 1906). Canning cheese. Paraffining
cheese (pp. 128-132). Clark and Crockett.

Vermont Agricultural Experiment Station, Burlington, Vt.

64 5th Ann. Rept. (1891). (a) Making cheese from
different qualities of milk (pp. 88-0 5). {h) Losses in cheese-
making (pp. 95-100). Cooke and Hills.

THE LITERATURE OF CHEESE-MAKING 463

Wisconsin Agricultural Experiment Station, Madison, Wis.

65 8th Ann. Rept. (1891). The feeding value of whey
(pp. 38-48). Henry.

66 nth Ann. Rept. (1894). (a) Influence of fat upon
yield of cheese (pp. 131-134). (6) Influence of fat on quality
of cheese (pp. 134-137). {c) Yield of cheese in factories from
different qualities of milk and at different seasons (pp. 137-
144). {d) Loss in curing cheese (pp. 145-146). {e) Cleaning
milk with a centrifugal cream-separator for cheese production
(pp. 146-149). Babcock.

(/) Sources of bacterial contamination of milk (pp. 150-
165). Russell.

(g) Effect of salt upon cheese fpp. 220-222). Decker.

67 12th Ann. Rept. (1895). (a) The centrifugal sepa-
ration • of casein and insoluble phosphates from milk (pp.
93-99). (6) Relation between yields of milk-solids and cheese
(pp. 100-120). (c) Relation between specific gravity and
solids of milk (pp. 120-126). (d) Hot iron test (pp. 133-134).
{e) Albumen cheese (pp. 13,4-136). Babcock.

(/) Effect of aeration on flavor of tainted curds in cheese-
making (pp. 127-129). (g) Gas-producing bacteria and their
relation to cheese (pp. 139-150). Russell.

(h) Influence of acid on texture of cheese (pp. 129-133).
Russell and Decker.

(t) Ripening milk before setting (pp. 136-138). Decker.

68 13th Ann. Rept. (1896). (a) Rise and fall of bac-
teria in Cheddar cheese (pp. 95-111). (6) Pure lactic acid
cultures in cheese-making (pp. 112-126). Russell.

69 14th Ann. Rept. (1897). (a) Unorganized ferments
of milk, a new factor in the ripening of cheese (pp. 161-193).
(6) Inflvience of temperature on the ripening of cheese (pp.
194-210). Babcock and Russell.

70 Bui. 60 (May, 1897). The cheese industry: its de-
velopment and possibilities in Wisconsin. Babcock and Rus-
sell.

71 Bui. 61 (Sept., 1897). The constitution of milk with
especial reference to cheese-production. Babcock.

72 Bui. 62 (Sept., 1897). Tainted or defective milks.
Their causes and methods of prevention. Russell.

73 15th Ann. Rept. (1898). (a) Effect of varying
strengths of rennet in curdling milk (pp. 31-34). " (6) Action
of rennet in watered milk (pp 35-36). (c) Action of common
salt on rennet action (pp. 37-41). {d) Methods of handling
sour milk :n making cheese (pp. 42-44). Decker

464 SCIENCE AND PRACTICE OF CHEESE-MAKING

(e) Improved curd test for detection of tainted milks
(pp. 45-53). Babcock, Russell and Decker.

if) Properties of galactase, a digestive ferment of milk
(pp. 77-87). {g) Distribution of galactase in cow's milk
(pp. 87-92). Babcock, Russell and Vivian.

(h) Relative absorption of odors in warm and cold milk
(pp. 104-109). Russell.-

74 16th Ann. Rept. (1899). (a) Coating cheese with
paraffin (pp. 153-155). Decker.

(b) Action of proteolytic ferments on milk with special
reference to galactase, the cheese-ripening enzym (pp. 155-
174). Babcock, Russell and Vivian.

75 17th Ann. Rept. (1900). Influence of rennet on
cheese-ripening (pp. 102-122). Babcock, Russell and Vivian.

76 18th Ann. Rept. (1901). (a) Print cheese (pp. 132-
135). Farrington.

(6) Influence of cold-curing on quality of cheese (pp.
136-161). Babcock, Russell, Vivian and Baer.

(c) Influence of sugar on nature of fermentation in
milk and cheese (pp. 162-176). Babcock, Russell, Vivian arid
Hastings.

_ 77 19th Ann. Rept. (1902). (a) Influence of cold-
curing on quality of cheddar cheese (pp. 150-164). (b) Infl-U-
ence of temperature approaching 60°F. on development of
flavor in cold-cured cheese (pp. 165-173). (c) Influence of
varying quantities of rennet on cold-cured cheese (pp. 174-
179). {d) Conditions affecting development of white specks
in cold-cured cheese (180-184). Babcock, Russell, Vivian and
Baer.

78 Bui. 94 (Aug., 1902). Curing of cheddar cheese
with reference to cold-curing. Consolidated cheese-curing
stations. Babcock and Rtissell.

79 Bui. 101 (July, 1903). Shrinkage of cold-cured
cheese during ripening. Experiments in paraffining cheese.
Babcock, Russell and Baer.

80 21st Ann. Rept. (1904). (a) Relation of flavor de-
velopment in cold-cured cheddar cheese to bacterial life in
same (pp. 155-163). Russell and Hastings.

81 Bui. 115 (Sept., 1904). The quality of cheese as
affected by rape and other green forage plants fed to dairy
cows. Baer and Carlyle.

82 22d Ann. Rept. (1905). (a) The Swiss cheese in-
dustry of Wisconsin; whey butter-making (pp. 157-180).
Farrington.

THE LITERATURE OF CHEESE-MAKING 465

(fe) Lactose-fermenting yeasts, the cause of abnormal
fermentation in Swiss cheese (pp. 207.-221). Hastings.

83 Bui. 128 (Sept., 1905). A Swiss cheese trouble
caused by a gas-forming yeast. Russell and Hastings.

84 Bui. 132 (Dec, 1905). The manufacture of whey-
butter at cheese-factories. Farrington.

85 23d Ann. Rept. (1906). (a) Development of factory
dairying in Wisconsin (pp. 100-106). Russell and Baer.

(b) Distribution of lactose-fermenting yeasts in dairy
products (pp. 107-115). Hastings.

86 24th Ann. Rept. (1907). (a) Influence of metals on
the action of rennet (pp. 134-159). Olson.

(6) Analyses of old cheese, skim-milk cheese, etc. (pp.
160-170). W oil and Olson.

87 Bui. 162 (April, 1908). Rusty cans and their effect
upon milk for cheese-making. Olson.

Dominion of Canada Dairy Commission, Department of
Agriculture, Ottawa, Can.

88 2d Ann. Rept. (1891-2). Experimental cheese-mak-
ing (pp. 146-153). Robertson and Ruddick.

89 3d Ann. Rept. (1892-3). Experiments in cheese
making (pp. 214-219). Robertson and Ruddick.

90 Rept. Conference Dairy Instructors and Experts
(1903). The cool-curing of cheese (pp. 96-110). Ruddick.

91 Rept. of Dairy Com'r (1906). (a) Cool-cured cheese
(pp. 8-9). (6) Management of a cool curing-room (pp. 13-14).
{c) Coating cheese with parafhn (pp. 14-15). Ruddick.

92 Rept. of Dairy Com'r (1907). (a) The cheese indus-
try (pp. 8-17). (6) Cool-cured cheese (pp. 17-18). Ruddick.

Ontario Agricultural College, Guelph, Ontario, Canada

93 Buls. 95 and 96 (1894) and 20th Ann. Rept. (1894).
(a) The composition of milk, whey and cheese in relation to
one another (pp. 20-33). Shuttleworth.

(6) Experiments in cheese-making (pp. 134-141). Dean.

94 Bui. 102 (May, 1896) and 22d Ann. Rept. (1896),
(pp. 41-56). Experiments in cheese-making. Dean.

95 23d Ann. Rept. (1897). (a) Experiments in cheese-
making (pp. 41-59). Dean.

(6) Bad flavor in cheese caused by undesirable bacteria
in water used in factory (pp. 141-144). Harrison.

96 24th Ann. Rept. (1898). Experiments in cheese-
making (pp. 40-64). Dean.

97 25th Ann. Rept (1899) Experiments in cheese'
making (pp. 54-65). Dean.

466 SCIENCE AND PRACTICE OF CHEESE-MAKING

98 26th Ann. Rept. (1900). Experiments in cheese
making (pp. 37-44). Dean.

99 27th Ann. Rept. (1901). Experiments in cheese-
making (pp. 44-55). Dean.

160 28th Ann. Rept. (1902). (a) Experiments in
cheese-making (pp. 64-68). Dean.

ip) Investigations regarding the ripening of cheese (pp.
40-41). Harcoiirt.

101 Bui. 120 (May, 1902). Bitter milk and cheese.
Harrison.

102 Bui. 121 (June, 1902). Ripening of cheese in cold
storage compared with ripening in ordinary curing-rooms.
Dean, Harrison and Har court.

103 29th Ann. Rept. (1903). Experiments in cheese-
making (pp. 60-76). Dean.

104 Bui. 130 (Dec, 1903). Bacterial contents of cheese
cured at different temperatures. Harrison and Connell.

105 Bui. 131 (Dec, 1903). Ripening of cheese in cold-
storage versus ordinary curing-rooms. Dean and Harcourt.

106 30th Ann. Rept. (1904). Experiments in cheese-
making (pp. 74-81). Dean.

107 31st Ann. Rept. (1905). Experiments in cheece-
making (pp. 115-126). Dean.

108 Bui. 141 (April, 1905). Gas-producing bacteria
and their effect on milk and its products. Harrison.

109 3 2d Ann. Rept. (1906). Experiments in cheese-
making (pp. 108-1 19). Dean.

Index to Literature of Cheese-Making

The reference numbers below indicate the serial
numbers (in heavy type) in the preceding list of publi-
cations, which go from i to 109.

Acidity of water-extract of cheese 20, 49

effect on texture of cheese 67

Acid, lactic, development of, in cheese-making 61

pure cultures in cheese-making 68

milk, handling of, in cheese-making 73

Acids, action upon casein 48

adsorption by casein 48

effect of, on enzyms in cheese 40, 44, 75, 77

effect of, on galactase in cheese-ripening 40, 74

effect of, on rennet in cheese-ripening 44, 75, 77

phosphates in cheese 49

relations to cheese-ripening 40, 44, 46

Adsorption of acids by casein 48

Aeration of milk 9, 16, 24, 25, 66

of milk by dipping 24

of milk by centrifugal separator 24, 66

Albumen cheese 67

Albumin in cheese 20-3 5

in milk 20-35

in whey 20-35

lost in cheese-making 20-35

relations of, to casein in milk 20-35

Amino acids in cheese 40, 43, 46, 74-75, 77

Ammonia in cheese 40, 43, 46, 74-75, 77

Analyses of cheese 20-35, 40, 44-46, 49, 60, 75

of milk 20-35

of whey 20-3 5

Bacteria, associative in souring of milk 11-14

digesting and cheese-solids 74

in udder 4, 40

producing gas and taints in cheese, 3, 10, 15, 67, 108

producing rust -red spots in cheese 38," 42

relation of, to cheddar-cheese flavors. . . .36, 67, 72

rise and fall of, in cheddar cheese 68

Bacterial contamination of milk 66

content of cheese kept at different temperatures, 104

468 SCIENCE AND PRACTICE OF CHEESE-MAKING

Bitter flavor in cheese and milk 46, 101

Breeds of cattle, comparative value of, for cheese produc-
tion 34

Brine-soluble protein in cheese 40, 44-46, 49

Butter-fat (see Fat).

Butter, whey 2, 132

Canning cheese 51,63

Casein, action of acids on 48

action of rennet and pepsin on 44

adsorption of acids by 48

amount in cheese 20-3 5

amount in milk 20-35

amount in whey 20-35

centrifugal separation of 67

influence on composition of cheese 20-35

influence on yield of cheese 20-35

lost in cheese-making 20-35

market value of, in cheese 32, 67

relation to albumin in milk 20-35

relation to fat in milk 20-35

relation to fat in skim -milk 20-25

relation to fat in skim-milk cheese 20-25

Centrifugal separation of casein from milk 67

Cheddar and stirred-curd processes compared 10, 20-25

Cheese, advantages of cold storage, 8, 10, 41, 45, 55, 58-59,

69, 76-80, 90-92, 102, 105

albumin in 20-3 5

amino acids in 40, 43-46, 74-75, 77

ammonia in , 40, 43-46, 74-75, 77

analyses of 6, 17, 20-35, 40, 43-46, 49, 77, 86

canning of 51,63

casein and albumin in 20-35

central curing-room for 41, 78, 90-92

Cheddar and stirred-curd processes compared,

10, 20-25

chemical changes in ripening of 45-46

chloroformed, changes in 40, 43-44

cold-cured, 8, 10, 41, 45, 55, 58-59, 69, 76-80,

90-92, 102, 105

cold-cured, composition of 45

cold-cured, white specks in 77

comparative production of, by different breeds

of dairy cattle 34

composition of .20-35, 40, 43-46

composition of, in relation to composition of milk,

20-35

INDEX TO LITERATURE OF CHEESE-MAKING 469

Cheese — continued

conditions used in manufacturing operations of, 20-35

consolidated stations for curing 78

cost of producing 34

Edam, manufacture and composition of 19, 27

effect of cold storage on moisture of, 45, 55, 58-59,

78-79, 90-92, 102, 105

effect of moisture on quality of 41, 45, 46

effect of paraffining. .10, 45-46, 55, 58-59, 63, 79, 91
effect of temperature in ripening, 8, 10, 39, 41,

45-46, 55, 58-59, 69, 76-80, 90-92, 102, 105
experiments in manufacture of, 6, 10, 17, 19, 20-35,
64, 67, 73, 81-82, 88-89, 93-100, 103, 106-107, 109

fat in 6, 10, 18, 20-35, 2>1 , 64, 67, 93

flavor and texture of, 20-25, 39, 45, 46, 56, 66-67,

76-78, 80, 93

gassy 3, 10, 15, 67, 108

Gouda, manufacture and composition of 19, 27

industry in New York 53

industry in Wisconsin 70, 82, 85

influence of milk on composition of 20-35

influence of milk on yield of 20-35

loss of fat in ripening of 41

loss of water in ripening of, 41, 45, 55, 58-59, 66, 69,

78-79, 90-92, 102, 105
loss in weight in ripening of (see Loss of water).

losses in making of 6, 10, 18, 20-35, 64, 93

made from milk containing added cream,

6, 10, 17, 20-25

made from normal milk rich in fat 26

made from skimmed milk 20-25

market value increased by cold storage (see Cold

storage) .

market value of casein and water in 32, 67

milk required to make one pound of , 20-35, 66, 93-100

paraffining of 10, 45-46, 55, 58-59, 63, 79, 91

print 76

production comparison of dairy breeds 34

quality improved by cold storage (see Cheese, cold

cured).

quick ripening, conditions for 46

rise and fall of bacteria in 68

sage 10

slow-ripening 46

solids in 20-35

soluble proteins in 40, 43-46, 74-75, 77

sources of carbon dioxid in 43

470 SCIENCE AND PRACTICE OF CHEESE-MAKING

Cheese — continued

stirred-curd, comparison with cheddar process,

10, 20-25
texture, relation of, to conditions of ripening,

39, 45-46, 55, 58-59, 76-80, 90-92, 102, 105

varieties of, descriptions and analyses 60

water in 20-35

yield and milk -fat 20-35, 66, 93

Cheese-curd (see Curd).

Cheese-factories, methods of paying for milk at,

32, 64, 67, 90-92, 93

Cheese-making, albumin lost in 20-35

casein lost in 20-3 5

cheddar process of 20-35

effect of adding cream. . ., 20-25

effect of adding skim-milk 20-25

effect of cutting curd hard and soft .... 20-35
effect of exposing milk to foul odors .... 24

effect of shutting up milk in cans 24

effect of tainted milk 23, 24, 73

effect of using different amounts of rennet,

20-25

experiments in 6, 18, 20-25, 90-100

fat lost in, 6, 18, 20-25, 64, 66, 67, 90, 92,

93-100

pure lactic acid cultures in 68

Cheese-ripening, effect of moisture 10, 41, 45, 68

effect of rennet 26, 44, 75, 77

effect of salt 46, 66

effect of size 4 1 , 46

effect of temperature, 8, 10, 41, 45-46, 55,

58-59, 69, 76-80, 90-92, 102, 105

use of hygrometer in 27, 68

Chemical changes in cheese 46

composition of cheese 20-25, 45-46

composition of milk 20-25

composition of whey 20-25

Chloroformed cheese (see Cheese, chloroformed).
Cold-cured cheese (see Cheese, cold-cured).
Composition of cheese, milk and whey (see Chemical com-
position).
Cream, addition to normal milk in cheese-making,

6, 10, 17, 20-25
Curd, comparison of ordinary and high temperatures of

heating 20-25

cutting of 20-3 5

effects of cutting coarse and fine 20-25

INDEX TO LITERATURE OF CHEESE-MAKING 4/1

Cirrd — continued

effects of cutting hard and soft 20-25

gassy 3, 10, 15, 67, 108

heating and stirring 20-35

temperature used in heating 20-35

time from cutting to drawing whey 20-35

Curd-test for detection of tainted milk 73

Curing-rooms 27, 41, 45-46, 68, 78

moisture suppl}'" in 27, 41, 68

Dairy, statistics of 52

cows, records of 75

schools 54

Drouth, effects of, on milk and cheese production 36

Edam cheese, manufacture and composition of 19, 27

Enzyms, action in cheese 40, 44, 74, 75

effect of chloroform, ether and formalin on,

40, 50, 73

effect of acids on 40, 44, 73

effect of heat on 40, 73

effect of salt on 40, 73

galactase 40, 69, 73, 74

in milk 40, 69, 73

in rennet 40, 44, 75, 77

Ether, effect of, on the action of enzyms 40, 74

Factories (see Cheese-factories).

Fat, amount in cheese 20-35

amount in milk 20-3 5

amount in whey 20-3 5

amount lost and recovered in cheese-making 20-35

in cheese, influence on ripening of cheese 41, 46

in milk, relation of, to casein in cheese 20-35

in milk, relation of, to fat in cheese 20-35

in milk, relation of, to composition of cheese 20-35

in milk, relation of, to yield of cheese 20-35

in milk, relation to casein in milk 20-35

in milk, relation to casein in skim -milk 20-25

in milk, yield of cheese for each pound of 20-35

Feeiing value of whey 65

Flavor of cheese 20-25

bitter, in cheese and milk ....,, 46, 101'

relation of bacteria to cheddar cheese 36, 67, 102

relation of conditions of ripening to, 39, 45-46, 55,

58-59, 76-78, 90-92, 102, 105

relation of yeasts to, in cheese 83, 108

sweet, in cheese 38

tainted, in milk and cheese 23-25, 72

Foods affecting flavor of cheese 20-2 5, 81

472 SCIENCE AND PRACTICE OF CHEESE-MAKING

Gas-producing bacteria in curd and cheese. .3, 10, 15, 67, 108

Gouda cheese, manufacture and composition of 19, 27

Hot -iron test 67

Lactation advancing, influence on casein and albumin in

milk 20-35

influence on cheese production. . .20-35

influence on fat in milk 20-35

influence on ratio of fat to casein, 20-35

Lactic acid, action on casein 48

development of, in cheese-making. 61

pure cultures in cheese-making 68

Loss of casein in cheese-making 20-25

carbon dioxid in cheese-ripening 43

fat in cheese-ripening 6, lOy 18, 20-35, 64, 93

milk constituents in cheese-making, 6, 10, 18,

20-35, 64, 93

solids in cheese-ripening 26, 41

water in cheese-ripening, 41, 45, 55, 58-59, 66, 69,

78-79, 90-92, 102, 105
weight in cheese-ripening (see Loss of water).
Manufacture of cheese (see Cheese-making).

Metals and rennet action 86

Milk, absorbed odors in 38,73

aeration of 9, 16, 24, 25, 66

albumin in 20-35

amount required for cheese 20-35, 66, 93

analyses of (see Analyses).

at cheese-factories, methods of paying for (see
Cheese-factories).

average composition of 20-35

care and handling of 5,16

casein in (see Casein).

cheese-producing constituents of 20-35

coagulation by rennet 20-35

composition of 20-3 5

composition of, relation to composition of cheese . . 20-35
constituents lost in cheese-making (see Loss in cheese-
making) .
containing added cream, relation of fat to casein in,

20-25

effect of exposing foul odors on cheese-making 24

effect of shutting up in cans 24

enzyms (see Enzyms in milk),
fat in (see Milk-fat).

fermentation of sugar in * . . 76

flavors in .3, 10, 15, 20-25, 39, 67, 81, 108

INDEX TO LITERATURE OF CHEESE-MAKING 473

Milk — continued

influence of composition of, on composition of cheese,

20-35
paying for, in cheese-making (see Cheese-factories).

relation of albumin and casein in 20-35

relation of casein and fat in 20-35

required to make one pound of cheese. . . .20-35, 66, 93

ripening before setting 67

skimmed, relation of fat to casein in 20-25

solids in 20-3 5

sour, handling of, in cheese-making 73

sugar in 20-35

tainted 3, 10, 15, 20-25, 67, 72, 108

Milks, difference in cheese-producing power of different,

20-35, 71

effect of adding cream to, in cheese-making 20-25

effect of adding skim-milk to, in cheese-making. . 20-25
effect of removing fat from, in cheese-making . ..20-25

Milk-cans, rusty and rennet action 87

Milk-fat, and cheese yield 20-35, 66, 93

as a basis for measuring cheese yield, 20-35, 66, 93
as a basis of paying for milk at cheese-factories
(see Cheese-factories).

cheese from normal milk rich in 26

cheese-producing power of 20-35

effect of drouth on 36

influence on composition of cheese 20-35

influence on yield of cheese 20-35

loss of, in cheese-making (see Loss of fat).

relation to casein in milk 20-35

relation to casein in skimmed milks 20-25

yield of cheese for each pound of 20-25, 66, 93

Milk-solids and cheese yield 20-35, 66

cheese-producing 20-35

in whey 20-3 5

relation, specific gravity to 67

New York State, cheese industry of 53

Nitrogen compounds in cheese . . . .20-35, 40, 43-46, 49, 74-75

in milk 20-35

water-soluble in cheese, 20-35, 40,

43-46, 49, 74-75

Paracasein in cheese 20-35, 40, 43-46, 49

Paraffin, effect of use on cheese, 10, 45-46, 55, 58-59, 63, 79, 91

Paraffining, effect on market value of cheese, 45, 55, 58-59,

63, 79, 91

Pepsin, commercial, action in cheese-ripening. . 44, 75

474 SCIENCE AND PRACTICE OF CHEESE-MAKING

Phosphates, acid m cheese 49

soluble in cheese 49

Products in cheese-ripening, cumulative and transient .... 46
Quality of cheese improved by cold storage (see Cheese,
cold-cured).

of cheese, influence of fat on 6, 17, 20-25, 66

Rennet, action in cheese-ripening 26, 44, 46, 75,77

efTect of metals on 86

effect of rusty cans on 87

efifect of salt on 73

effect of varying strength of, in coagulating

milk 73

effect of watered milk on 73

Rennet -extra'ct, amount used in cheese-making 20-35

comparison of commercial and home-
made 20

comparison of commercial and pepsin. . . .44
relation to cheese-ripening. 26, 44, 46, 75, 77
Ripening of cheese (see Cheese-ripening),

Ripening milk before setting 67

Room, curing for cheese (see Curing-rooms).

Rusty spots in cheese 38, 42

Sage cheese 10

Salt, effect on action of rennet in cheese-ripening . .40, 44, 46
effect on action of enzyms in cheese-ripening, 40, 44, 46

effect on moisture in cheese 46, 66

effect on quality of cheese 46, 66

brine, cheese protein soluble in 40, 44-46

Schools, dairy 54

Separator, centrifugal, cleaning milk with 24, 66

removing casein from milk with. . .67

Skim-milk, effect of use in cheese-making 20-25, 37

relation of fat to casein in 20-25, 37

ripening of cheese made from 46

Solids in cheese 20-35, 67

in milk 20-35, 67

in whey 20-35, 67

Sour milk, making cheese from 12>

Souring of milk, associative action of bacteria in 11-14

Specific gravity, relation of milk-solids to 67

Spots, rusty, in cheese 38, 42

Starter, use in cheese-making 20-25, 68

Statistics of the dairy 52

Stirred-curd and cheddar processes, comparison of, 10, 20-25

Sugar in cheese 20-3 5 , 49

in milk 20-35

in whey 20-3 5

Sweet flavor in cheese 38

INDEX TO LITERATURE OF CHEESE-MAKING 475

Swiss cheese, manufacture of 82

yeast fermentation in • 82, 83, 85

Taints in milk and cheese (see Cheese and milk).

Temperature in cheese-making 20-35

in cheese-ripening (see Cheese-ripening).

Texture of cheese, influence of acid on 67

relation to conditions of ripening,
39, 45-46, 55, 58-59, 76-80, 90-92, 102, 105

Udder, bacteria in and enzyms in milk 4, 40

Varieties of cheese, descriptions and analyses of 60

Water in cheese 20-35

effect on commercial quality, 41, 45-46,

55, 58-59, 79

market value of 45-46

value to consumers and dairymen 46

in milk 20-35

in whey , 20-35

Weight lost by cheese in ripening, 41 45, 55, 58-59, 66, 69,

78-79, 90-92, 102, 105

Whey, albumin in 20-3 5

analyses of 20-3 5

butter 2, 132

casein in 20-3 5

composition of 20-3 5

feeding value of 65

solids in 20-35

Wisconsin, cheese industry of 70

Yeasts in cheese-making, troubles from 82, 83, 85

Yield of cheese and composition of milk 20-35

Index

Page

Absorption of flavors oy milk. . . 6
Absorption of flavors by milk

from foods 7

Acid body, cause, prevention, etc.

of 122

Acid calcium phosphate in cheese-
ripening 358

Acid flavor in cheese, cat:se, pre-
vention, etc 116

Too little 82

Too much 82

Acid, lactic, action in cheese-
ripening 356

Fermentation 292

Abnormal 295

From milk-sugar 149

Acid salts, effect on rennet action 308

In cheese-ripening 334

Acid test, Mann's 428

Acid-cut color 89, 129

Acidity and body of cheese 52

Color of cheese 52

Contraction of curd 51

Expulsion of whey 52

Finish of cheese 53

Flavor of cheese 52

Keeping quality of cheese. ... 53

Rennet action 51

Texture of cheese 52

In cheese, excessive, causes of. 51

Cheese-making, control of . . . . 53 .

In curd and cheese, effects of . , 45
In curd and cheese, conditions

of 45

Insufficient, cause of 50

Of cheese, excessive, causes of 50

Of milk.. 152

Of milk in ripening 21

Of milk, quick test for 429

Of whey from curd at salting. 37

Of whey in heating curd 30

Of whey when cheddaring is

complete 35

Of whey when drawn from curd il

Of whey, testing 429

Relation of, to moisture, in curd 47

Test 426

Test for ripening milk 21

A.cids, action on casein 143

Effect on rennet action 306

In cheese-ripening, action of. . 356

Use of, in cheese-making 63

Page

Aeration of milTc 12

Albumin in milk and cheese-mak-
ing 139

Relation to casein 172

Alkaline salts, effect on rennet

action 308

Alkaline tablet test, Farrington's 428

Alkalis, action on casein 145

Effect on rennet action 308

American cheddar cheese, sizes of 44

Amino acids in cheese 331

Ammonia in cheese 331

Appearance of cheese, definition

of 90

Architecture of cheese-factories. , 98

Ash of milk 150

Ayrshire milk, composition of

cheese from 232

Babcock test for fat in milk 423

Bacillus lactici acidi ' . . . 292

Bacteria, action in cheese-ripening 371
Action of sunlight, chemicals,

etc 289

Ball-shaped 287

Changes produced by 28^

Corkscrew-shaped 287

Description of 287

Digesting 295

Distribution of 281

Effect of temperature 288

Food requirements of 288

Gas-producing 29?

Growth and reproduction 287

Kinds of 287

Producing bad flavors 296

Rodyshaped 287

Bacterial infection of milk,

sources of 4

Bitter flavor. 83

Body, acid, cause, remedy, etc. , of 122

Cause, etc., of defects in 121

Corky 87

Crumbly 88

Curdy 87

Dry, cause, remedy, etc 121

Firm 87

Gritty 88

Mealy 88

Meaty 87

Of cheese and acidity 52

Of cheese, definition of 86

Of cheese , effect of moisture on 47

477

478 SCIENCE AND PRACTICE OF CHEESE-MAKING

Page

Body of cheese, testing 87

Overdry 88

Pasty 87

Perfect 87

Salvy 87

Silk> 87

Smooth 87

Solid 87

Stiff 87

Watery 88

Waxy 87

Weak 87

Borax, effect on rennet action . . . 308

Boxes, cheese, stenciling 77

Boxing cheese for shipment 77

Brands on cheese, use of 72

Breed, influence of, on fat and

casein 165

Breeds of cows, casein and albu-
min in milk of 173

Brine-soluble protein in cheese-
ripening 359

Brine-soluble substance from

casein , 147

Butter and cheese, making of . . . 69
6 utter- fat (see Milk-fat).
Butter, whey, ^nanufacture of. . . 65
Calcium phosphate, insoluble, in

cheese-ripening 358

Soluble in cheese-ripening 358

Calcium salts, action on para-
casein 304

Efifect on rennet action 306

In milk, action of rennet on . . . 304
Calculating cheese yield, accuracy

of methods 226

Cheese yield from fat 213, 224

Cheese yield from fat and casein

216, 225
Cheese yield for different per-
centages of water 224

Dividends at cheese-factones. . 279

Milk-solids 438

Per cent of casein in milk 170

Yield of green cheese 211

Yield of ripe cheese 225

lave of cheese 71

Of milk at factory 17

Of milk at farm 3

!!asein, action of acids on 143

Action of alkalis on 145

Action of enzyms on 147

Action of heat on 146

Action of rennet on 146

Action of salts on 146

Amount of, in milk . 161

And albumin, relations of, in

milk 172

And fat, average in factory milk 1 72
And fat, calculating cheese

yield from 216, 220

And fat in milk, relation of . . . . 164

Page

Casein and fat, paying for milk

on basis of 269

And fat, relation to cheese yield 187
And fat, relation of, in factory

milk 167, 169

And paracasein, relation of . . . . 305

And stage of lactation 162

Brine-soluble substance from. 147
Calculated, and fat, paying for

milk on basis of . 276

Calculating amount of, in milk 170

Change of, into paracasein .... 303

Composition of 141

Differing from paracasein. . . . 303

Digestion by rennet 306

Functions of, in cheese 178

In cheese-factory milk 163

In milk, effect of drouth on. . . 163

In milk, effect of pasturage on 163

In milk, insoluble 142

In milk of different breeds of

cows 161

Loss of, in cheese-making 194

Test for 440

Caseoses in cheese 330

Central curing-station 394

Cheddar cheese, American, sizes of 44

Defects in _ 113

From pasteurized milk 60

Cheddaring curd, operations of . . 32

Cheddaring operation, objects of 34

Operation, when complete. ... 35

Texture produced by . 35

Velvety appearance of curd in 35

Cheese, acid flavor in 116

Acidity and finish of 53

Acidity and keeping-quality of 53

American cheddar, sizes of . . . . 44

Amino acids in 331

Ammonia in 331

And butter, making of . 69

And whey, distribution of milk

constituents in 203

Body of, and acidity 52

Boxing for shipment 77

Calculating yield of 211

Care of.. 71

Caseoses in 330

Causes of excessive acidity in . . 50

Causes of excessive moisture in 46

Causes of insufficient acidity in 50

Changes in fat of, in ripening. . 331

Cheddar, defects in 113

Club, making of . . 405

Commercial qualities of. .... . 80

Composition, effect of skim-
ming milk on 234

Composition of, and milk con

stituents 231

Composition of, and quality. . . 243

Conditions of acidity of 45

Conditions of moisture in ... . 45

Color of, and acidity 52

INDEX

479

Page
Cheese, cottage, composition of 40-*

Cottage, making of 400

Covering with paraffin 74

Cracked rinds m 133

Creanx. making of 405

Defects in flavor of 115

Definition of body of 86

Definition of flavor of 84

Definition of texture of 84

Drawing to shipping point. ... 78

Dressing of 43

Edam, making of 406

Effect of freezing on quaHty of 390
Effect of paraffining on loss of

weight of 319

Effects and control of moisture

in 45

English sage, making of 399

Excessive acidity in, cause of . . 50

Finish in 91

Flavor of, and acidity 52

Flavors, causes of 375

Food flavors in 119

From Ayrshire milk, composi-

. tion of 232

From Guernsey milk, composi-
tion of 232

From Holstein milk, composi-
tion of 232

From Jersey milk, composition

of .. . 232

From normal milk, composition

of 231

From pasteurized milk. ...... 60

From rich milk, composition of 237
From skimmed milk, composi-
tion of 233

Functions of casein in 179

Functions of fat in 177

Functions of water in 180

Gas-holes in 86

Gassy, green fodder a source of 7

Gouda, making of 415

Home-trade 62

How to sell 78

Immediate removal from fac-
tory . 393

Judging commercial qualities of

80, 91

Mechanical holes in 86

Methods of grading 95

Methods of scoring 93

Milk constituents and yield of 186
Milk-sugar, changes of, in

ripening 333

Moisture in, effects on weight

lost in ripening 323

Moisture in, right amount. . . . 382

Moldv, cause, etc 134

Neuf hatel, making of 404

Off flavors in 116

Paranuclein in 330

Page

Cheese, paying for 79

Peptones in 330

Placing in curing-room 71

Poison 68

Profits from proper ripening of 391
Proteins in, agents changing. . 355
Quality of, in rel tion to mois-
ture.. 381

Quick-ripening 60

Red spots in 89

Ripe, calculating yield of 22 5

Sale of 71

Sampling of 80

Shipment of 71, 73

Size of, effect of weight lost in

ripening 320

Skim-milk. 250

Slow ripening 60

Standards of states 241

Standard of United States. ... 237

Stilton, making of 398

Testing 80

Testing body of 87

Testing color of 88

Testing flavor of 81

Testing texture of 84

Texture of, and acidity 52

Texture of, effect on loss of

moisture 324

Turning of 72

Unclean surface of, remedy. . . 133

Uncolored 89

Unripe, acid salts in 328

Unripe, chemical compounds in 327

Unripe, milk-sugar in 328

Unripe, neutral salts in 328

Unripe, proteins in 328

Unripe, salt in 329

Water in, value to consumers. . 383

Water in, value to- dairymen. . 380

Weighing for shipment 76

White specks in 88, 332

With different percentages of

water, calculating yield of. . 224

Yeasty, cause, prevention, etc. 126
Yield, accuracy of methods of

calculating ■. . . 226

Yield and solids, paying for

milk on basis of 2C1

Yield, calculating from fat, 213, 225
Yield, calculating from fat and

casein 216, 220

Yield, factors of 186

Yield of, effect of skimming

milk on 234

Yield of, effect of starters on. . 69
Yield, relation of fat and casein

to 187

Yield, relation of milk-fat to. . 204

Yield, relation of water to. . . . 198

Cheese-box, proper appearance of 78

Cheese-boxes, stenciling 7 7

480 SCIENCE AND PRACTICE OF CHEESE-MAKING

Page

Cheese-brands, use of 72

Cheese-factories, calculating divi-
dends at.. 279

Paying for milk at 253

Cheese-factory architecture 98

Association 453

Co-operation 452

Construction 97

Curing-room in 102, 394

Drainage 99

Equipment 106

Furnishings 106

Losses in ripening 379

Management 451

Method of disinfecting 132

Milk, casein in 1 63

Milk, composition of 175

Milk, fat in 159

Milk, relation of fat and casein 169
Milk, variations in composition

of 176

Organization 451

Plans of construction 105

Water supply of 99

Cheese-making and micro-organ-
isms 285

Care of milk for 3

Clean milk for 3

Colostrum milk in 12

Control of acidity in 53

Control of moisture in 48

First steps in IS

Functions of casein in 178

Functions of milk constituents

in.. 177

Functions of milk-sugar in. . . . 182
Functions of salts of milk in. . 184

Granular process of 55

Judging milk for 12

Loss of casein in 194

Loss of milk-fat in 188

Loss of milk constituents in. . . 188

Paying for milk for 253

Relation of enzyms to 285

Ripening milk for 18

Science of 137

Soaked-curd process of 57

Stirred-curd process of 55

System of records for 16

Use of acids in 63

Use of pepsin in 64, 312

Use of starter in 21

Cheese-producing solids in milk. . 200
(]^heese-ripening. . . . 313, 327, 354, 379

Acid salts in 334

Action of acids in 356

Action of bacteria in 371

Action of galactase in 368

Action of pepsin in 365

Action of rennet on 346, 361

Causes of chemical changes of, 354
Chemical changes in 32?

Page

Cheese-ripening, changes in 314

Changes in proteins in 330

Chemical, definition of 337

Conditions affecting quality

324, 38S

Cumulative products in 350

Effect of moisture on chemistry

of 340

Effect of moisture of air on

weight lost in 317

Effect of paraffin coating on

319, 389

Effect of salt on 343

Effect of size 3-42

Effect of size on weight lost in

320. 387
Effect of temperature on loss of

weight in 315

Effect of temperature on

quality 324, 388

Effect of time on chemical

changes of 337

Factory losses in 3 79

Gases in 334

Influence of products on 351

Loss of weight in 314

Measuring rate of 336

Milk-sugar in 357

Neutral salts in 334

Proper conditions 394

Temperature and weight lost. . 386

Transient products in 350

Why moisture affects 353

Cheese-scoring cards 94

Chemical changes in cheese-ripen-
ing 32 7

Of cheese-ripening, causes of. . 354
Of cheese-ripening, effect of

temperature on 338

Of cheese-ripening, effect of

time on 337

Chemical compounds in unripe

cheese 327

Chemical products of cheese-
ripening, effect on process. . 351
Chloroform, effect on rennet

action 308

Chymosin of rennet 299

Clean flavor 82

Milk for cheese-making 3

MUk, how to obtain 8

Cleaning and disinfecting, method

of 132

Close texture 86

Coagulating action of rennet, ex-
planation of 302

Coagulation by rennet, imperfect,

causes of 23

Of milk, effect of temperature 309

Color, acid-cut, cause, etc 89, 129

Defects in, cause, etc 129

High 89

INDEX

4»i

Page

Color, light 89

Mottled, cause, etc 89, 129

Of cheese and acidity 52

Of cheese, testing of 88

Pale, cause, remedy, etc 129

Perfect 88

Rusty-spot, cause, etc 131

Seamy, cause, etc 89, 130

Straight 88

Streaked 89

Translucent 88

Wavy 89

Coloring-matter, adding to milk. 22

Colostrum milk in cheese-making 12

Commercial qualities of cheese. . . 80

Score-cards 94

Starter 19

Composition of cheese and milk

constituents 231

Of cheese and quality 243

Of cheese, effect of skimming

milk on 234

Of cheese-factory milk 175

Of cheese from Ayrshire milk. . 232

Of cheese from Guernsey milk 232

Of cheese from Holstein milk. . 232

Of cheese from Jersey milk. . . 232

Of cheese from normal milk. . . 231

Of cheese from rich milk 237

Of cheese from skimmed milk. 233

Of cottage-cheesfc 404

Of milk, diagram showing. ... 195

Of whey 195

Constituents of milk 139

Of milk, conditions affecting. . 155

Construction of cheese-factory... 97

Of curing-room 102

Corky body 87

Cottage-cheese, composition of. . 404

Making of 400

Qualities of 403

Yield of 403

Cows, fat in milk of breeds 157

Cowy flavor 83

Cracked rinds, cause, etc 133

Cream cheese, making of 405

Crumbly body 88

Cubes of curd 26

Curd, acidity of whey when drawn

from 31

Amount of salt to iise on 38

Behavior after cutting 27

Cheddaring, operations of 32

Conditions of acidity of 45

Conditions of moisture in 45

Contraction of, and acidity. . . 51

Cubes of 26

Effects and control of acidity in 45
Effects of cutting fine or coarse 2 7
Effects of pressing at low tem-
peratures 41

Page

Curd , effects of pressmg at high

temperatures 41

Film on 29

Firming of 29

Heating 29

How high to heat 29

How to apply salt to 39

How to cut 26

How to press 42

Length of strings on hot iron, at

salting 37

Matting of 32

Milling objects of 35

Piling of 32

Preparation of hoop for 42

Pressing 40

Pressing, objects of 41

Pressing of, regulation of 42

Purpose of cutting 25

Regulation of heating 30

Removal of whey from 31

Rule for heating 30

Salting 37

Salting, effects 39

Stirring after cutting 28

Stirring to dry 32

Stringing of, on hot iron. .31, 35, 37
Temperature of, at pressing. . . 40
Texture of, produced by ched-
daring 35

Velvety appearance in ched-
daring 35

"When to cut 25

When to heat 29

When to mill 35

When to press 40

When to remove whey from ... 31

When to salt 37

Curd-test, Wisconsin 435

Curdy body ' 87

Curing-room at cheese-factory. . . 394

Construction of 102

Effect of moisture in, on weight

lost 317

Placing cheese in 71

Curing-stations, central 394

Cutting curd fine or coarse, effect

of 27

Curd, rules for 25

Stirring curd, after 28

Daisies, size of 44

Defects in body, cause, preven-
tion, etc 121

In Cheddar cheese 113

Color, cause, etc 129

In finish, cause, etc 129

In flavor 115

Digesting action of rennet 306

Bacteria 295

Dirt in milk, tests for 433

Disinfecting, method of 132

Dissolving action of rennet 306

482

SCIENCE AND PRACTICE OF CHEESE-MAKING

Page
Dividends, calculation of, at

cheese-factories 279

Drainage of cheese-factory 99

Dressing of cheese 43

Droath, effect upon relation of fat

and casein 168

Effect on milk-casein 163

Dry body, cause, remedy, etc., of 121

Drying curd by stirring 32

Edam cheese, making of 406

Educational score-cards 94

English sage cheese, making of . . 399

Enzym, pepsin 312

Rennet, conditions of action. . 306

Rennet, digesting action of . . . 306

Enzyms, action on casein 147

And cheese-making 285, 291

In milk 297

Of milk 153

Equipment of cheese-factory. ... 106

Export Cheddar cheese, size of . . . 44

Factors of cheese yield 136

Factory architecture 98

Construction and material for, 97, 98

Drainage 99

Equipment 106

First care of milk at 17

Location of 97

Method of disinfecting 132

Milk, fat and casein in 172

Plans of construction 105

Site of 97

Water-supply of 99

Farrington's alkaline tablet test. 428

Fat, amount of, in milk 156

And calculated casein, paying

for milk on basis of 276

And casein average in factory

milk ; 172

And casein, calculating cheese

yield from 216, 220

And casein, effect of drouth

upon relation of . 168

And casein in milk, influence of

breed on 165

And casein in milk, relation of 164
And casein, influence of lacta-
tion on relation of 166

And casein, paying for milk on

basis of _ 269

And casein, relation of, in fac-
tory milk 169

And casein, relation to cheese

yield: 187

Calculating cheese yield from

213, 224

Functions of, in cheese ....... 177

In cheese, changes in ripening 331

In cheese-factory milk 159

In milk 140

In milk, Babcock test for 423

^n milk, effect of pasturage on 160

^ . . . "^^9
Fat, in milk, influenced by lacta-
tion 158

In milk, losses in cheese-making 1 88

In milk, relation to cheese yield 204

In whey 190, 197

Lost in cheese-making, condi-
tions favoring 192

Paying for milk on basis of . . . 2 58
Plus 2 method of paying for

milk 264

Globules in milk 140

Fermentation, definition of 285

Lactic acid 292

Lactic acid, abnormal 295

Test -f3S

Ferments, characteristics of 286

Chemical 286, 29 1

Definition of 285

Organized 286

Unorganized 286, 291

Film on curd 29

Finish and acidity of cheese 53

Defects in, cause, etc 129

In cheese 91

Of cheese, effects of moisture on 48

Firm body 87

Firming curd 29

First steps in cheese-making. ... IS
Fish-eye texture, cause, remedy,

etc 126

Fishy flavor 83

Flat flavor 82

Flats, size of 44

Flavor, bitter 83

Clean 82

Cowy 83

Fishy 83

Flat 82

Fruity 83, 118

High 82

Hydrogen sulphid 83

Low 82

Of cheese and acidity 52

Of cheese, defects in 115

Of cheese, definition of 84

Of cheese, effect of moisture on 48

Of cheese, testing 81

Perfect 82

Quick 82

Rancid S5

Sour 83

Stable 83

Strong 82

Sweet 83

Tainted S3

Tallowy 83

Too little acid 82

Too much acid 82

Weedy 83

Flavors, absorption of, by milk. . 6

Acid, in cheese . 116

Absorption from food by milk i

INDEX

483

Page

Flavors, bacteria producing bad 296

Food, in cheese 119

Fruity, in cheese 118

Of cheese, causes of 375

Off, in cheese 116

Food flavors in cheese, cause,

remedy 119

Foods, absorption of flavors from,

by milk 7

Formaldehyd, effect on rennet

action 308

Freezing cheese, effect on quality 390

Fruity flavor 83, 118

Functions of casein in cheese-
making 178

Of milk constituents in cheese-
making 177

Of milk-sugar in cheese-making 182
Of salts of milk in cheese-mak-
ing 184

Of water in cheese 180

Galactase 297

Action in cheese-ripening 368

And cheese-ripening 368

Properties of. .... 298

Gases in cheese-ripening 334

Gas-holes in cheese ,86

Gas-producing bacteria 295

Gassy milk and cheese, green fod-
der as a source of. 7

Texture, cause, prevention, etc. 124

Gouda cheese, making of 415

Grading cheese 95

Granular process of cheese-mak-
ing 55

Greasy texture, cause, prevention,

etc 125

Green fodder, source of gassy milk

and cheese 7

Gntty body 88

Guernsey milk, composition of

cheese from 232

Heat, action of, on casein 146

Effect of, on rennet 310

Heating curd, rule for 30

Curd, temperature of 29

Curd, when to begin 29

High color 89

Flavor 82

Holstein milk, composition of

cheese from 232

Home-made rennet-extract 300

Home-trade cheese 44, 62

Hoop, preparing to receive curd. • 42
Hot iron, stringing of curd on

31, 35. 37

Hot-iron test 439

Hydrogen-sulphid flavor 83

Jersey milk, composition of cheese

from 232

Judging cheese 80, 91

Cheese, scale of points for 92

Paga
Judging cheese, milk for cheese-
making 12

Keeping quality of cheese and

acidity . 53

Of cheese, effect of moisture on 48

Lactation and casein in milk. ... 162

Effect on fat in milk 158

Effect on relation of fat and

casein 165

Lactic acid, action in cheese-
ripening 356

Fermentation 292

Fermentation, abnormal 29 5

From milk-sugar 149

Lactometer, Quevenne, use of. . . 438
Lactose (see Milk-sugar).

Light color 89

Location of factory 97

Longhom cheese, size of 44

Loose texture, cause, remedy, etc.

86, 123

Loss of casein in cheese-making. . 194

Of fat, conditions favoring. . . , 192

Of fat in cheese-making 190

Of moisture, effect of cheese

texture on 324

Of weight in cheese-ripening,

effect of temperature on ... . 315
Losses of milk constituents in

cheese-making 188

Low flavor 82

Manns' acid test 428

Marschall test for ripening milk

21, 430

Matting of curd 32

Mealy body 88

Meaty body 87

Mechanical holes in cheese 86

Metals, effect on rennet action. . 309
Micro-organisms, action in cheese-
ripening 371

And cheese-making 285

Milk, absorption of flavors by. . . 6

Acidity of ........ 152

Acidity of, in ripening 21

Addition of rennet-extract to. . 23

Adding coloring matter to. . . . 22

Aeration of 12

Albumin and cheese-making. . 139

Ash of ISO

Albumin , relation to casein ... 172

At cheese^factories, paying for. 253
Ayrshire, composition of

cheese from 232

Baboock test for fat in 423

Care of, for cheese-making. ... 3

Bacterial infection of, sources. 4

Cheese-factory, composition of 175

Cheese-factory, fat in. 159

Clean, for cheese-making 3

Clean, how to obtain. . 8

Colostrum in cheese-making. . . 12

4^4 SCIENCE AND PRACTICE OF CHEESE-MAKING

Page

Milk, conditions affecting con-
stituents of 155

Constituents and cheese yield. 186
Constituents and composition

of cheese 231

Constituents, distribution in

whey and cheese 203

Constituents, functions of, in

cheese-making 177

Constituents, losses of, in

cheese-making 188

Constituents of 139

Diagram showing composition

of 195

Enzyms in 153, 297

Factory, casein in 163

Factory, relation of fat and

casein in. ....... 169

Factory, variations in composi-
tion of 176

Finding degree of ripeness of . . 21

First oare of, at factory 17

Freshly drawn, effect of rennet

on 310

Gassy, green fodders a source of 7
Guernsey, composition of

cheese from ..-...• 232

Holstein, composition of cheese

from 232

Jersey, composition of cheese

from 232

Judging for cheese-making. ... 12
Normal, composition of cheese

from 231

Pasteurized, cheese from . . . 60, 404
Paying for, on basis of cheese

yield and solids 261

Paying for, on basis of fat 258

Paying for, on basis of fat and

casein 269

Paying for, on basis of fat_and

calculated casein. . , 276

Paying for, on basis of "fat

plus 2" 264

Paying for. on basis of weight 257
Relation of casein and albumin

in 172

Relation of fat and casein in. . 164
Rich, composition of cheese

from 237

Ripening for cheese-making. . . 18

Salts of 150

Skimmed, cheese from 250

Skimmed, composition of cheese

from 233

Skimming, effect on composi-
tion and yield of cheese. . . . 234

Tests for dirt in 435

Treatment of, after milking. . . 10

Water in 139

Whey and cheese-solids in. . . . 201

Page
Milk-cans, rusty, effect on rennet

action 309

Milk-casein, action of acids on. . . 143

Action of alkalis on 145

Action of enzyms on 147

Action of heat on 146

Action of rennet on 146

Action of salts on 146

Composition of 141

Effect of drouth on 163

Effect of pasturage on 163

In factory milk 163

Physical condition of 142

Rule for calculating amount of 170
Strength of rennet in coagulat-
ing.. 302

Variations 161

Milk-fat 140

And breeds of cows 157

And lactation 158

Effect of pasturage on 160

Functions in cheese 177

In factory milk 159

In whey 190

Losses of, in cheese-making. . . 188
Paying for milk on basis of . . . . 258

Relation to cheese yield 204

Variation of 157

Milks, different, effects of rennet

on 311

Milk-pails, sanitary 10

Milk-solids, calculation of 438

Milk-sugar 148

Functions of, in cheese-making 182

In cheese, changes of 333

In cheese-ripening 357

In unripe cheese 328

Lactic acid from 149

Milling curd, objects of 35

Moisture, deficient, in curd, effects

of 45

Effect on body of cheese 47

Effect on chemistry of cheese-
ripening 340

Effect on finish 47

Effect of, on flavor of cheese ... 48
Effect on keeping quality of

cheese 43

Effect on texture of cheese. ... 47
Excessive, in curd, effects of . . 46
How much cheese should have 382
In cheese, affecting quality. ... 381
In cheese, effect on weight lost

in ripening 323

In cheese-making, control of . . 48
In curd and cheese, effects of . . 43
In cheese, effect of texture on

loss of 324

Of air, effect on weight lost in

ripening 317

Relation of, to acidity in curd. 4>

INDEX

485

Page
Moisture, variation in loss with

different kinds of cheese. ... 321
Why it affects ripening of

cheese 353

Moldy cheese, cause, etc 134

Monrad test for ripening milk . . 21, 432

Mottled color 89, 129

Natural starter 18

Neufchatel cheese from pasteur-
ized milk, making of 404

Neutral salts in cheese-ripening. 334
Off flavors in cheese, cause, rem-
edy, etc 116

Open texture, cause, prevention. 123

Overdry body 88

Package, cheese 91

Pale color, cause, remedy, etc. . . 129
Paracasein, action of calcium salts

on 304

And casein, relation of 305

Change of casein into 303

Digestion by rennet 306

Distinction from casein 303

Precipitation by calcium salts. 304
Paraffin coating on cheese, effect

on quality 389

Covering cheese with 74, 387

Paraffining cheese, effect on

weight lost in ripening 319

Paranuclein in cheese 330

Pasteurized milk, cheese from ... 60
Pasturage, eft'ect on casein in milk 163

Pasty body 87

Patrons' statement . 451

Paying for milk at cheese-factories 253
On basis of cheese yield and

solids 261

On basis of fat 258

On basis of fat and calculated

casein 276

On basis of fat and casein 269

On basis of "fat plus 2" method 264

On basis of weight 257

Pepsin, commercial, action in

cheese-ripening 365

Enzym 312

Method of testing. 434

Use in cheese-making 64, 312

Peptones in cheese 330

Perfect body 87

Color 88

Flavor 82

Texture 85

Picnic cheese, size of 44

Piling of curd 32

Pin-hole texture 86

Plansof factory construction. . . . 105

Poison in cheese 68

Porous texture , 86

Pressing curd 40

At high temperatures, effects of 41
At low temperatures, effects of 41

Page

Pressing curd, conditions of 40

How regulated 42

Objects of 41

Temperature of curd at 40

Print cheese, size of . . 44

Profits from proper ripening of

cheese 391

Propagation of starter 20

Protein, brine-soluble, in cheese-
ripening 359

Proteins, changes in cheese-ripen-
ing 330

In cheese, agents changing. ... 355

In unripe cheese 328

Qualities, commercial, of cheese. . 80
Quality of cheese and composition 243

Affected by moisture 381

Effect of freezing on 390

Effect of paraffin coating 389

Effect of temperature on 388

Quevenne lactometer, use of . . . . 438

Quick flavor 82

Quick-ripening cheese 60

Rancid flavor 83

Records, system of, for cheese-
making 16

Red spots in cheese 89

Rennet action and acidity 51

Effect of acid salts on 308

Effect of acids on 306

Effect of alkaline salts on 308

Effect of alkalis on 308

Effect of borax on 308

Effect of calcium salts on 306

Effect of chloroform on 308

Effect of formalin on 308

Effect of metals on 309

Effect of rusty milk-cans on . . . 309

Effect of salt on 308

Effect of temperature on 309

In cheese-ripening 361

On calcium salts of milk 304

On casein 146

On different milks 311

Rennet coagulation, effect of

water on 307

Explanation of 302

Imperfect, causes of 23

Rennet, effect of heat on 310

Effect of sunlight on 310

Effect, on cheese-ripening 346

Effect on freshly drawn milk. . 310

Source of . . 300

Strength of, in coagulating milk 302

Test, Marschall 430

Test, Monrad 432

Rennet-enzym, conditions of

action 306

Dissolving action of 306

Rennet-extract, addition of, to

milk 23

Amount to use 22

486 SCIENCE AND PRACTICE OF CHEESE-MAKING

Page
Rennet-extract commercial .... 301

How made 300

Method of testing 433

Rennin of rennet. . 299

Rich milk, composition of cheese

from 237

Rinds, cracked, cause, etc 133

Ripe milk, acidity of . . . .' 21

Ripeness of milk, finding degrees

of 21

Ripening milk for cheese-making 18

Milk, objects of 18

Of cheese 313

Of cheese, acid salts in 334

Of cheese, changes in . 314

Of cheese, changes in proteins

in . 330

Of cheese, chemical changes in 327
Of cheese, effect of temperature

on weight lost in 315

Of cheese, measuring rate of . . 336

Of cheese, neutral salts in 334

Of cheese, profits from proper. 391
Rule for calculating casein in milk 170
Rusty milk-cans, effect on rennet

action 309

Rusty spots, cause, etc 131

Sale of cheese 71

Salt, amount to use on curd 38

Effect on cheese-ripening 343

Effect on rennet action 308

How to apply to curd 39

In cheese 89

In cheese, testing 90

In unripe cheese 329

When to put on curd 37

Salting curd, effects of 39

Curd 37

Salts, acid, in unripe cheese 328

Action of, on casein 146

Neutral, in unripe cheese 328

Of milk ISO

Of milk, functions of, in cheese-
making 184

Salvybody 87

Sampling cheese 80

Sanitary milking-pails 10

Scale of points for judging 92

Science of cheese-making 137

Score-cards, commercial 94

Educational 94

Scoring cheese, method of 93

Seamy color 89, 130

Septic-tank drainage 100

Shape of cheese, effect of weight

lost in ripening 320

Shipment, boxing cheese for. ... 77

Of cheese 71

Weighing cheese for 76

Shipping cheese 73

Silky body 87

Site of factory 97

Feg8

Size and loss of weight 387

Size of cheese, effect on weight

lost in ripening 320

Skim-milk cheese 250

Skimming milk, effect of, on com-
position of cheese 234

Effect on yield of cheese 234

Skimmed milk, composition of

cheese from 233

Slow-ripening cheese 60

Smooth body 87

Soaked-curd process of cheese-
making 57

Solid body 87

Solids, cheese- producing, in dif-
ferent milks 200

Solids, not fat in milk, calculation

of 439

Sour flavor 83

Specks, white, in cheese-ripening 332

Square cheese, size of 44

Stable flavor 83

Standard for cheese, United

States 237

Standards of states for cheese. . . 241

Starter, commercial 19

Effect on yield of cheese 69

Natural.. 18

Preparation of 18

Propagation of 20

Use of, in cheese-making 21

Stenciling cheese-boxes 77

Stiff body 87

Stilton cheese, making of 398

Stinkers, cause, prevention 116

Stirred-curd process of cheese-
making 55

Stirring curd after cutting 28

Stirring curd to dry it 32

Straight color 88

Streaked color 89

Stringing of curd on hot iron ,31,35,37
Strings of curd on hot-iron in

cheddaring 35

Length of, at salting 37

Strong flavor. 82

Sugar in cheese-ripening 357

In milk 148

Milk, in unripe cheese 328

Sunlight, effect on rennet 310

Supplies for cheese-factory 106

Sweet flavor 83

Swiss-hole texture 86

Tainted flavor 83

Tallowy flavor •.•••-.• "^^

Temperature and loss of weight in

cheese-ripening 315

Effect on rennet action 309

Effect of, on chemical changes
in cheese-ripening. ........ 338

Influence on loss of weight in
ripening 386

INDEX

487

Page
Temperature of curd at pressing. 40

of heating curd .• • • • 29

Of ripening, effect on quality. . 388
Test for acidity of milk, whey, etc. 426

For casein 440

For dirt in milk 435

Hot-iron 439

For acidity for ripening milk. . 21

Testing acidity of whey 429

Body of cheese 87

Cheese 80

Cheese for salt 89

Flavor of cheese 81

Methods of 423

Pepsin, method of 434

Rennet-extract, method of. . . . 433
Texture, cause, etc., of defects in 121

Close .. 86

Defects in, cause, prevention,

etc , 121

Fish-eye, cause, prevention, etc. 126
Gassy, cause, prevention, etc.. 124
Greasy, cause, prevention, etc. 125

Loose 86, 123

Mechanical holes. . 86

Of cheese and acidity 52

Of cheese, definition of 84

Of cheese, effect of moisture on 47
Of cheese, effect on loss of

moisture 324

Of cheese, testing. 84

Of curd in cheddaring 34

Open, cause, prevention, etc.. . 123

Perfect 85

Pin-hole 86

Porous 86

Swiss-hole 86

Translucent color 88

Turning cheese. . ._ 72

Twins, Cheddar, size of 40

Unclean surface, cause, etc 133

Uncolored cheese 89

United States cheese standard. . . 237
Water, calculating cheese yield

for different percentages of . . 224

Effect on rennet action 307

Fxinctions of, in cheese 180

In cheese, value to consumers. 383
In cheese, value to dairymen. . 380

InmiDc 139

Relation of, to cheese yield. . . . 198

Water-supply of factory 99

Watery body 88

WaVi color 89

Waxy body 87

WeaK body 87

Weedy flavor 83

Weighing cheese for shipment. . . 76
Weight, loss in cheese-ripening. . 314

Page

Weight, lost in cheese-ripening,

effect of moisture of air on 317
Lost by paraffined cheese ..319, 387
Lost in ripening, effect of mois-
ture in cheese on . 323

Lost in ripening, effect of size

of cheese on. ..... 320, 387

Lost in cheese-ripening, effect

of temperature on _ 315

Lost in ripening at factories. . . 380
Lost in ripening, influence of

temperature on 386

Lost in ripening, reduction of. 383

Paying for milk by 257

Whey, acidity of, at salting curd 37
Acidity of, in heating curd. ... 30
Acidity of, when drawn from

curd •.••■. .• • "^^

And cheese, distribution of milk

constituents in 203

Composition of 195

Distribution and value of 66

Expulsion of, and acidity 52

Fat in 190

Removal of, from curd 31

Testing acidity of . 429

Variations of constituents. . . . 197

When to remove from curd. . . 31

Whey-butter, manufacture of . . . 65

Whey-solids in different milks. . . 201

White specks in cheese 88, 332

Wisconsin curd-test 435

Yeasts . . 296

Yeasty cheese, cause, prevention,

etc 126

Yield of cheese, accuracy of

methods of calculating 226

Of cheese and milk constituents 186
Of cheese, calculating from fat

213, 224
Of cheese, calculating from fat

and casein 216, 220

Of cheese, effect of skimming

milk on 234

Of cheese, effect of starters on 69

Of cheese, factors of 186

Of cheese, methods of calculat-
ing 211

Of cheese, relation of fat and

casein to 187

Of cheese, relation of milk-fat

to 204

Of cheese, relation of water to 198
Of cheese with different per-
centages of water, calculation

■ of 224

Of cottage-cheese 403

Of ripe cheese, calculation of . . 225
Young American cheddars. size of 4^

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First Principles of Soil Fertility

By Alfred Vivian. There is no subject of more vital
importance to the farmer than that of the best method
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The Study of Corn

By Prof. V. M. Shoesmith. A most helpful book to all
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The Cereals in America

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The Forage and Fiber Crops in America

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The Book of Alfalfa

History, Cultivation and Merits. Its Uses as a Forage
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Clean Milk

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Feeding Farm Animals

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Profitable Dairying

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Practical Dairy Bacteriology

By Dr. H. W. Conn, of Wesleyan University. A complete
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Modern Methods of Testing Milk and Milk
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Animal Breeding

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Forage Crops Other Than Grasses

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SoiUng Crops and the Silo

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The Study of Breeds

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Clovers and How to Grow Them

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03>

The New Egg Farm

By H. H. Stoddard. A practical, reliable manual o.
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Poultry Feeding and Fattening

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Turkeys and How to Grow Them

Edited by Herbert Myrick. A treatise on the natural
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Bean Culture

By Glenn C. Sevey, £».S. A practical treat-^e on the pro-
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Celery Culture

By W. R. Beattie. A practical guide for beginners and a
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Tomato Culture

By Will W. Tracy, The author has rounded up in this
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The Potato

By Samuel Fraser. This book is destined to rank as a
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Dwarf Fruit Trees

By F. A. Waugh. This interesting book describes in detail
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Farm Grasses of the United States of America

By William Jasper Spillman. A practical treatise on
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The Book of Corn

By Herbert Myrick, assisted by A. D. Shambia, E. A.
Burnett, Albert W. Fulton, B. W. Snow, and other most
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The Hop — Its Culture and Care. Marketing and
Manufacture

By Herbert Myrick. A practical handbook on the most
approved methods in growing, harvesting, curing and sell' ig
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Tobacco Leaf

By J. B. Killebrew and Herbert Myrick. Its Culture and
Cure, Marketing and Manufacture. A practical handbook
on the most approved methods in growing, harvesting, curing,
packing and selling tobacco, with an account of the opera-
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contents of this book are based on actual experiments in field,
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Farmer's Cyclopedia
of Agriculture

A Compendium of Agricultural Science and Prac-
tice on Farm, Orchard and Garden Crops, and the
Feeding and Diseases of Farm Animals

^y EARLEY VERNON WILCOX. Ph. D.
and CLARENCE BEAMAN SMITH. M. Sc

Associate Editors in the Office of Experiment Stations, United States
Department of Agriculture

THIS is a new, practical, and complete
presentation of the whole -subject of ag-
riculture in its broadest sense. It is de-
signed for the use of agriculturists who
desire up-to-date, reliable information
on all matters pertaining to crops and stock, but
more particularly for the actual farmer. The
volume contains

Detailed directions iox the culture of every
important field, ofchard« and garden crop

;^rown in America, together with descriptions of
their chief insect pests and fungous diseases, and
remedies for their control. It contains an ac-
count of modern methods in feeding and handling
all farm s'-ock, including poultry. The diseases
which affect different farm animals and poultry
are described, and the most recent remedies sug-
gested for controlling them.

Every bit of this vast mass of new and useful
information is authoritative, practical and easily
found, and no effort has been spared to include
all desirable details. There are between 6,000
and 7,000 topics covered in these references, and
it contains 700 royal 8vo pages and nearly 500
superb half-tone and other original illustrations,
making the most perfect Cyclopedia of Agricul-
ture ever attempted.

Handsomely bound in clolh, -^3.50; h at f morocco
{"Very sumpiuotij), •^4-.50t postpaid

ORANGE Jlf DD COMPANY, ^'"2' f"" "^ "«""' "'" ''""'' "

People's Gas Riiilding, Chicago, II.

a9)

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vv\^\

BOSTON PUBLIC LIBRARY

3 9999 05676 912 6

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Full text of "The science and practice of cheese-making : a treatise on the manufacture of American Cheddar cheese and other varieties : intended as a text-book for the use of dairy teachers and students in classroom and workroom ..."

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